Showing posts with label Astronomy. Show all posts
Showing posts with label Astronomy. Show all posts

Friday, December 14, 2018

The Star of Bethlehem Explained

The Adoration of the Magi (circa 1305) by Giot...
The Adoration of the Magi (circa 1305) by Giotto, purportedly depicting Halley. 
(Photo credit: Wikipedia)
For centuries astronomers have speculated about the famous Star of Bethlehem, which the three Magi (the three wise men/the three kings) followed to the place of Christ's birth. Of course, the star may defy scientific explanation altogether, and be viewed as a miracle. Nevertheless, various astronomical theories have been proposed, including that the star may have been a comet, or a supernova (an exploding star), or a "planetary conjunction" (a gathering of planets in one part of the sky). In this column, we'll examine two of today's most popular theories, both of which hold that the planet Jupiter played a key role.

First, though, it's useful to recall what the Bible says about the most famous star in history:

"After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, "Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him." When King Herod heard this he was disturbed, and all Jerusalem with him. When he had called together all the people's chief priests and teachers of the law, he asked them where the Messiah was to be born. "In Bethlehem in Judea," they replied, "for this is what the prophet has written: "'But you, Bethlehem, in the land of Judah, are by no means least among the rulers of Judah; for out of you will come to a ruler who will shepherd my people Israel."

Then Herod called the Magi secretly and found out from them the exact time the star had appeared. He sent them to Bethlehem and said, "Go and search carefully for the child. As soon as you find him, report to me, so that I too may go and worship him." After they had heard the king, they went on their way, and the star they had seen when it rose went ahead of them until it stopped over the place where the child was. When they saw the star, they were overjoyed. On coming to the house, they saw the child with his mother Mary, and they bowed down and worshipped him. Then they opened their treasures and presented him with gifts of gold, frankincense and myrrh. And having been warned in a dream not to go back to Herod, they returned to their country by another route." Matthew 2:1-12

If you Google "Star of Bethlehem," the Web site of a best selling DVD, The Star of Bethlehem, ranks at the very top. The DVD features American attorney, Sunday school teacher, and amateur astronomer Rick Larson, who has conducted extensive research into the scientific, historical and theological aspects of the Star of Bethlehem.

After a careful review of scripture, Larson identifies nine characteristics of the star that, he believes, any scientific theory of the star must meet in order to be compliant with Christian belief. For example, we can see from Matthew 2:1-12 that the star signified the birth of a king, that it was associated with the Jewish nation, and that, "it stopped over the place where the child was" - Bethlehem.

Larson then draws on his study of ancient history to address the all-important issue of the year that King Herod died. According to Matthew 2, after the birth of Jesus, an angel appeared to Joseph in a dream, urging Joseph to flee Israel and take Mary and the infant Jesus to Egypt so as to avoid the wrath of Herod, who had issued orders that all male children in his realm under the age of two be executed. Later in Matthew 2, an angel informs Joseph that Herod has died and that it is safe to return to Israel. So the argument goes that we should subtract two years from the year of Herod's death to estimate the year Jesus was born. Knowing Jesus' estimated year of birth allows astronomers to run computer simulations of the positions of the stars and planets as they appeared in the night sky during the approximate time frame of Jesus' birth.

Most historians and biblical scholars put Herod's death at around the year 4 BC, meaning Jesus would have been born sometime around 6 BC. But Larson points to recent historical research arguing that Herod died in 1 BC, which would place Jesus' birth year around 3 BC.

Using modern astronomical software, Larson then runs computer simulations of the night sky over the Middle East in 3 and 2 BC and reaches two remarkable results - both involving the planet Jupiter.

Viewing the night sky from Jerusalem in mid-September of 3 BC, an observer could see Jupiter, known as the "King Planet" (from classical mythology) in conjunction with (i.e., close to) the star "Regulus," known as the "King Star. Furthermore, Regulus is in the constellation (area of the night sky) "Leo," which represents a lion, which was the symbol of Judah.

Furthermore, Larson notes, the planets in the night sky move relative to the 'fixed' stars: If you note the position of, say, Jupiter relative to stars such as Regulus from night to night, then you'll note that Jupiter generally moves eastward across successive night skies. However, occasionally, Jupiter will seemingly halt its eastward movement, and begin moving westward across successive night skies. (This is an optical effect - called "retrograde motion" - resulting from the fact that Earth's orbit around the sun lies within Jupiter's orbit around the sun. Jupiter, Saturn and other planets outside Earth's orbit demonstrate the same retrograde motion as we view those planets from Earth, which itself is in motion in its orbit about the sun. Our planet's orbital motion combined with the orbital motions of the outer planets cause the retrograde motion optical effect.) As Jupiter switches from moving eastward to moving westward (or vice versa), Jupiter appears to be stationary relative to the stars. In this way, Jupiter appeared to stop "over the place where the child was," as we read in Matthew 2.

But, Larson argues, this conjunction of Leo with Regulus may have marked the conception of Jesus. If we run the computer simulation of Jerusalem's night sky forward nine months into June of 2 BC, we find that Jupiter and the planet Venus - two of the brightest planets in the night sky - come into extremely close conjunction, so much so that the two planets appear together as one, very bright 'star' in the night sky!

So the conjunction of Jupiter with Regulus in 3 BC, and/or the conjunction of Jupiter with Venus nine months later in 2 BC, may very well have been the star the Magi followed.

If we return to the Google search results for "Star of Bethlehem," we find the Web site of professional astronomer Michael Molnar, who takes a different approach to the star of Bethlehem. In his book, The Star of Bethlehem: The Legacy of the Magi, Molnar explores not only the Biblical account of the star but also the point of view of the Magi, whom Molnar argues were astrologers/astronomers: In the ancient Roman world, astrology and astronomy were indistinguishable. The Magi were held in high esteem in Roman culture and were considered to be very knowledgeable, indeed, wise men.

Molnar, who does not believe in astrology, nevertheless has extensively researched the astrological beliefs prevalent in the Roman world. He argues that modern astronomers who think about the Star of Bethlehem make a mistake by focusing on what spectacular displays may have appeared in the night sky around the time of Jesus' birth, such as the appearance of a very bright star. The focus on amazing heavenly displays is a bias of relatively modern astronomers, Molnar argues. The Magi of ancient Rome, Molnar explains, were primarily concerned with the logic of their astrological system, which placed primary emphasis on the locations and arrangements of the planets in the night sky - the sequence of planets in the night sky, what constellations they were in, how far above the horizon they appeared at sunrise, etc.

So, for example, the fact that Jupiter and Venus were so close to one another that they appeared as one, very bright star would not necessarily be significant to the Magi. Rather, the Magi would be much more interested in knowing whether Jupiter was to the east of Venus or to the west of Venus, the constellation(s) in which the two planets were located, and how high above the horizon the two planets appeared at sunrise.

Accepting the consensus view of most scholars that Herod likely died in 4 BC, Molnar considers the positions of the planets in the night sky two years earlier - in 6 BC - and finds a particular arrangement of the planets Jupiter, Saturn, Venus, Mars and Mercury, together with the Moon and Sun, that would have been of great astrological significance to the Magi, indicating that a king was being born. Furthermore, the centring of this particular planetary arrangement in and around the constellation Aries was significant, in part because in Roman-era astrology Aries was the sign of Judea. So to the Magi, the arrangement of the stars and planets in 6 BC led them to believe that a great king was born in Judea. Moreover, we should bear in mind Jupiter's retrograde motion, as well as the spirit of revolution in the air at the time - the notion that a messiah would soon lead the Jewish people in revolt against the Roman Empire. All of these factors combined, then, would naturally have induced the Magi to travel to Jerusalem - the capitol city of Judea - to inquire as to the whereabouts of the newborn king.

So whether we take the more Biblically-oriented analysis of Larson or the more astrologically-oriented analysis of Molnar, we find compelling scenarios that support the notion that the Star of Bethlehem was a real, historical event.

    Richard Pickering is an astronomer for Name A Star Live, which lets you express your feelings in a romantic, meaningful way by 'naming a star' for a loved one. While no star-naming service can change the scientific designations of stars, only Name A Star Live makes it real by providing you: Virtual Planetarium astronomy software; an opportunity to view your star live using an online telescope; and the launch of your star name into space!
    Article Source: EzineArticles

Friday, November 30, 2018

Achromatic versus Apochromatic Lenses in Telescopes

Achromatic telescope made by Dollond with handle by Hooke - Photo: Wikimedia
In 1733, an Englishman, Chester Moore Hall, created the Achromatic refracting lens.  His design limited the color aberrations by using two pieces of glass that were both ground and polished.  These lenses usually were employed to see red and blue light.  However, the design does not block out all of the rainbow of color around the images.

Achromatic lenses are made from a convex and a concave lens.  The concave lens is usually made out of Flint glass, and the convex from Crown glass.  They form a weak lens together and can bring two wavelengths of light into a single focus.

Apochromatic refracting lenses are made to view red, green, and blue light wavelengths. The first ones were designed by the German physicist, Abbe.  

Some type of fluorite or extra-low dispersion glass is also used and the ending result is a crisp clear image free of the rainbow of color around it.  These types of refracting lenses are more expensive than achromatic lenses.

Apochromatic lenses require lenses that can handle three color crossings.  They are usually made from expensive fluoro-crown glass, abnormal flint glass, or transparent liquids that are used in the space between the glass.  These newer designs allowed for the objects to be free of color around the edges, and they produced way fewer aberrations than achromatic lenses.

Prices on these types of refracting lenses can run high depending on the size aperture you need.  Two to three-inch apertures for Achromatic refractors can run between $250 to $1000.  Three to five-inch apertures for Apochromatic refractors can run between $2000 to $10,000.  Decide which kind you will be using before you buy one.  You may just want to look at the night sky or you may want to gaze into the next galaxy.

Saturday, October 27, 2018

Eyepieces for Telescopes

Okulare - Eyepieces - Photo: Wikipedia
Beginner astronomers need to be careful with these items as they tend to go way overboard.  There are various designs and different lenses for different viewings.  You need to figure out what you will be looking at and go from there.  You may need two to three different eyepieces, but no more than that.  Here is a simple guide to the different eyepieces and cost involved.

The most popular is the Plossl.  It uses four to five elements and has a wider field of view than Orthoscopic lenses.  It usually ranges from 50-52 degrees.  They run between $50-$150.

For general use, the Orthoscopic lenses were considered the best.  They use four elements and are good for planetary viewing.  They have a 45-degree field of view.  They run between $40-$100.

The Kellner is a general purpose lens.  It has a three element design and a 40-45 degree field of view.  They run between $30-$50.

The Ramsden and Huygenian are good solar lenses.  They have two element designs.  They are supplied with the least expensive telescopes and have very narrow fields of view.  They cost between $25-$40.

Barlow lenses are a great piece to have.  They can double or triple the magnification of your eyepiece.  They run between $60-$100.

Erfles are not as favorable today.  They use six elements and a 60-65 degree field of view.  They run between $75-$150.

Televue has come out with some designs for eyepieces.  The six element Panoptic has a 67-degree field of view.  It runs between $200-$400.  The other is a seven to eight element Naglers.  This lens has an 82-degree field of view and runs between $175-$425.

Pentax also makes a seven element lens, the SMC-XL, that runs around $250 each.  It is thought that these exceed what the Televues can do.

(Article around the year 2007)

Thursday, October 11, 2018

Bonding with the Universe.

Milk Way - Photo: Pixabay
As parents, we often worry about what our children are getting excited about.  We hope we can guide them to “bond” with healthy things like a love of learning, of family and of healthy social activities.  But we also worry they will bond with the wrong people like internet stalkers or the wrong crowd at school.  Wouldn’t it be great if we could harness that tremendous energy and desire to latch onto something and bond with it and help our children “bond” with the universe through a love of astronomy?

Kids love to get excited about what you are excited about.  So their lots of ways you can “spring” the fun of astronomy on them that will jump-start them on a long and happy exploration of the hobby of astronomy.  Here are a few to get your imagination going.

* Work it into an evening in the backyard.  If you know the night sky will be particularly exciting the night of a big family barbecue, plan to have some blankets out there.  Then as everybody else is playing Frisbee, just lay out a blanket, lay flat on your back and start staring up into the sky with binoculars.  Like the old prank of staring at a faraway spot to get people’s interest, your kids will see what you are doing and what to know what is going on.  As you let them take a peek, their curiosity will take off like a wildfire and they are hooked.

* A surprise visit to the country.  Sometimes it is hard to see the vast display of stars from within the city.  So if you announce that you are going to show them a surprise one night and have them pile into the car, their curiosity will be going wild as you leave the city.  When you find that quiet park, field or lakeside spot, all you have to do is point up and say “just look” and the magnificence of the night sky will do the rest.

* A special Christmas gift.  You can buy your children an affordable and durable beginner’s telescope along with some easy star maps written just for kids.  Imagine when they open this exciting gift and want to know how to use it.  Don’t be surprised if you are setting up the new telescope in the snow to show them the great things they will see in the cosmos with the gift that Santa wanted them to have.  The gift of astronomy.

* Unleash the power of a meteor shower on them.  You can keep your eye on the events that are predicted for the sky watchers in your area.  When the next big meteor shower is about to explode over your area, watch the weather for a clear night and get your kids excited about what they are about to see.  As the lights begin to go off overhead and you create fun and interesting narration to this dramatic display, the children will be addicts for life for the great experiences that can be had as students of astronomy.

* Plan a surprise event in with something you are already doing.  For example, on vacation, you can plan your route on a cross-country trip to bring you within visiting distance of one of the great multimillion dollar telescopes in this country.  By contacting them ahead of time, you can be sure they are conducting a tour that coincides with your visit.  Just imagine if they can look up at a telescope that is bigger than their house and maybe look through the eyepiece as some amazing cosmic sight, it will be the hit of the vacation.

Astronomy is a great activity to introduce on a family camping trip.  As the family sits around the fire after a fun night of camping, all you have to do is just look up and go “Wow, look at that!” When those little heads look up, they will look back down changed children, children in love with the stars.

Astronomy is a healthy passion for your kids and one they can grow with their entire lives.  And there is probably no better gift you can give them than the love of the stars, of science and of nature that is all wrapped up together when your kids bond with the universe through astronomy.

Friday, August 24, 2018


Hartebeesthoek Radio Astronomy Observatory
Hartebeesthoek Radio Astronomy Observatory 

(Photo credit: Wikipedia)

For most of us, the idea of astronomy is something we directly connect to “stargazing”, telescopes and seeing magnificent displays in the heavens.  And to be sure, that is the exciting area of astronomy that accounts for its huge popularity.  So to the uninitiated, the idea of “radio astronomy” seems strange.  There are two reasons for that.  First is that humans are far more visual than audio oriented.  And the second is that radio astronomy doesn’t really involve “listening” to the cosmos except to the extent that scientists who use this sophisticated form of “stargazing” do not rely on the visual study to conduct their work.

To appreciate what is really exciting about radio astronomy, first, we have to shift how we view astronomy.  That is because to professional astronomers, studying the universe is more about frequencies than it is about visual documentation of phenomenon.  This takes us back to Physics 101.

Light, obviously, is the physical phenomenon that empowers our ability to use our visual confirmation system, e.g. our eyes to appreciate something, in this case, the stars.  So when we look up at the heavens, we can see the light emitting from a star or reflecting from a planet or moon.  In many cases, if we see a faraway star, we are actually seeing it hundreds or thousands of years ago because that is how long it takes for that light to cross the universe and be visible in our sky.  That alone is a pretty mind-blowing idea.

Now light itself is a pretty strange substance.  But to our astronomy scientists, light is just another energy that exists in a certain frequency.  Now, we tend to think of frequencies when we talk about sound waves.  In scientific terms light, energy and sound are just a few forms of the same thing, frequencies of energy that are emulating from a source.

Now we get to why radio astronomy is so necessary.  The range of frequency that light occupies in the big spectrum of frequencies is really pretty small.  To put that more bluntly, we can only “see” a tiny part of the universe that is actually there.  Now when you look up in the night sky and it is so overwhelming, when you then that we are seeing just a tiny amount of what is actually going on up there, again, our minds can get pretty overwhelmed.

Radio astronomy uses sophisticated sensor equipment to study ALL of the frequencies of energy coming to us from the cosmos.  In that way, these scientists can “see” everything that is going on out there and so get a precise idea of how the stars look, behave now and will behave in the future.

For some of us who have heard about radio astronomy, we think of it in terms of “listening” for signs of life in the universe.  And yes, SETI, or “the Search for Extra-Terrestrial Intelligence” is a part of radio astronomy, albeit a tiny part.  But of much greater importance is how radio astronomy has empowered serious astronomers (that is those who get paid to do it) to study stars many light years away, to study black holes which we could never see with our telescopes and to gather research and data about the whole of the universe that otherwise would be impossible to know and understand.

This is important work that is constantly ongoing in the world of astronomy.  It is worth keeping up with and learning more about as we have barely scratched the surface in our brief discussion today.

But understanding how important radio astronomy is will only deepen and make more meaningful your love and grasp of this big field of knowledge known as astronomy.

Saturday, July 21, 2018

Beyond the Naked Eye

Picture: Flickr
It’s hard to say when in our lives each of us become aware of this thing called “astronomy”.  But it is safe to say that at some point on our lives, each and every one of us has that moment when we are suddenly stunned when we come face to face with the enormity of the universe that we see in the night sky.  For many of us who are city dwellers, we don’t really notice that sky up there on a routine basis.  The lights of the city do a good job of disguising the amazing display that is above all of our heads all of the time.

So it might be that once a year vacation to a camping spot or a trip to a relative’s house out in the country that we find ourselves outside when the spender of the night sky suddenly decides to put on its spectacular show.  If you have had that kind of moment when you were literally struck breathless by the spender the night sky can show to us, you can probably remember that exact moment when you could say little else but “wow” at what you saw.

That “Wow” moment is what astrology is all about.  For some, that wow moment becomes a passion that leads to a career studying the stars.  For a lucky few, that wow moment because an all-consuming obsession that leads to them travelling to the stars in the space shuttle or on one of our early space missions.  But for most of us, astrology may become a pastime or a regular hobby.  But we carry that wow moment with us for the rest of our lives and begin looking for ways to look deeper and learn more about the spectacular universe we see in the millions of stars above us each night.

To get started in learning how to observe the stars much better, there are some basic things we might need to look deeper, beyond just what we can see with the naked eye and begin to study the stars as well as enjoy them.  The first thing you need isn’t equipment at all but literature.  A good star map will show you the major constellations, the location of the key stars we use to navigate the sky and the planets that will appear larger than stars.  And if you add to that map some well done introductory materials into the hobby of astronomy, you are well on your way.

The next thing we naturally want to get is a good telescope.  You may have seen a hobbyist who is well along in their study setting up those really cool looking telescopes on a hill somewhere.  That excites the amateur astronomer in you because that must be the logical next step in the growth of your hobby.  But how to buy a good telescope can be downright confusing and intimidating.

Before you go to that big expense, it might be a better next step from the naked eye to investing in a good set of binoculars.  There are even binoculars that are suited for star gazing that will do just as good a job at giving you that extra vision you want to see just a little better the wonders of the universe.  A well-designed set of binoculars also gives you much more mobility and ability to keep your “enhanced vision” at your fingertips when that amazing view just presents itself to you.

None of this precludes you from moving forward with your plans to put together an awesome telescope system.  Just be sure you get quality advice and training on how to configure your telescope to meet your needs.  Using these guidelines, you will enjoy hours of enjoyment stargazing at the phenomenal sights in the night sky that are beyond the naked eye.

Tuesday, May 29, 2018

Galileo's Telescope

Galileo Galilei showing the Doge of Venice how to use the telescope - Photo: Wikimedia
Rumors of a Dutchman creating a device that would bring objects closer so you could see them more clearly reached Galileo in 1609.  He started using the device after he refined it to a 10-power telescope and made some amazing discoveries with it.  In 1610, he looked around Jupiter to find three satellites all in a straight line.  When he looked back, they were in all directions.  He surmised they were orbiting Jupiter and that, if this were true, then the Earth wasn't the center of the universe.  This theory went against what the church taught.  

The church believed Galileo to be quite wrong.  They said everything he could see in his new telescopic device went against everything the Bible said.  Galileo argued that even the interpreters of the Bible could have made a mistake in the interpretation.  He was accused of heresy, but proclaimed innocent and told not to teach any of the Copernican belief system.

Unbeknownst to the church, Galileo continued to study Jupiter and the movements of its moons.  He also started working on a paper about the ocean's tides.  He was brought before the court for trying to teach the Copernican system after being told not to.  He was placed under house arrest and until his death in 1642, he investigated even more areas of science.  

He made even more fascinating discoveries with his telescope.  He found there companion stars next to Saturn which was actually the edges of the rings that encircle the planet.  He found spots on the sun's surface and watched Venus go through its many phases from a planet down to a sliver of light.

He published his findings in a book called “The Starry Messenger” in 1610.  People were quite excited about some of the theories found in the book.  Imagine finding for the first time that the Earth was round, and not flat.  What would you think?

Wednesday, April 18, 2018

How to Look Up

Vitebsk amateur astronomical observatory (MPC COD B42) - Photo: Wikimedia
The beauty of astronomy is that anybody can do it.  From the tiniest baby to the most advanced astrophysicist, there is something for anyone who wants to enjoy astronomy.  In fact, it is a science that is so accessible that virtually anybody can do it virtually anywhere they are.  All they have to know how to do is to look up.

It really is amazing when you think about it that just by looking up on any given night, you could see virtually hundreds of thousands of stars, star systems, planets, moons, asteroids, comets and maybe an even an occasional space shuttle might wander by.  It is even more breathtaking when you realize that the sky you are looking up at is for all intents and purposes the exact same sky that our ancestor's hundreds and thousands of years ago enjoyed when they just looked up.

There is something timeless about the cosmos.  The fact that the planets and the moon and the stars beyond them have been there for ages does something to our sense of our place in the universe.  In fact, many of the stars we “see” with our naked eye are actually light that came from that star hundreds of thousands of years ago.  That light is just now reaching the earth.  So in a very real way, looking up is like time travel.

Everybody knows how to look up.  Children first discover the amazing light show on display for free every clear night by just looking up.  You can probably remember that very first time you noticed that explosion of stars above you when you were a child.  Now it is time to foster that same love of astronomy in your own children.  You have to teach them how to look up.

While anyone can look up and fall in love with the stars at any time, the fun of astronomy is learning how to become more and more skilled and equipped in star gazing that you see and understand more and more each time you look up.  Here are some steps you can take to make the moments you can devote to your hobby of astronomy much more enjoyable.

* Get out of town.  The furthermost you can get from the lights of the city, the more you will see in the night sky.

* Know what you are looking at.  It is great fun to start learning the constellations, how to navigate the night sky and find the planets and the famous stars.  There are websites and books galore to guide you.

* Get some history.  Learning the background to the great discoveries in astronomy will make your moments stargazing more meaningful.  It is one of the oldest sciences on earth to find out the greats of history who have looked at these stars before you.

* Get a geek.  Astronomy clubs are lively places full of knowledgeable amateurs who love to share their knowledge with you.  For the price of a coke and snacks, they will go stargazing with you and overwhelm you with trivia and great knowledge.

* Know when to look.  Not only knowing the weather will make sure your star gazing is rewarding but if you learn when the big meteor showers and other big astronomy events will happen will make the excitement of astronomy come alive for you.

And when all is said and done, get equipped.  Your quest for newer and better telescopes will be a lifelong one.  Let yourself get addicted to astronomy and the experience will enrich every aspect of life.  It will be an addiction you never want to break.

Saturday, February 24, 2018

Historical Timeline for TELESCOPES

Hubble - Photo: Wikimedia
It seems all the technology for telescopes started back in 2560 BC.  Artisans in ancient Egypt polished rocks, glass, and semi-precious stones to make eyes for the sarcophagi.  What follows is some major points in the history of how telescopes came to be today.
  • In 470 BC, Mozi, a Chinese philosopher, focused the sun's rays by using concave mirrors.
  • In 4 BC, Seneca the Younger used water to magnify letters and words.
  • In 23, Pliny the Elder discovered doctors using a crystal ball with the sun's rays beaming through it to cauterize wounds.
  • In the ninth century, telescopes were possibly made from Visby lenses, a Middle Eastern glass.
  • In 1520, Leonard Digges, an English mathematician, invented two telescopes – Reflecting and Refracting.
  • In 1608, A Dutch lensmaker, Hans Lippershey, applied for a patent on a design for a telescope.
  • In 1609, Galileo improved on Lippershey's design and renamed it “perspicillum” - An Italian word for a telescope.
  • In 1616, Niccolo Zucchi invented a reflecting telescope.
  • In 1663, James Gregory, a Scottish mathematician, produces a telescope with a parabolic primary mirror and an elliptical secondary mirror.
  • In 1668, Isaac Newton designed a telescope using a parabolic primary mirror and a flat diagonal secondary mirror.
  • In 1733, Chester Moore Hall created the achromatic lens.
  • In 1880, Ernst Abbe invented the first orthoscopic eyepiece.
  • In 1910, The Ritchey-Chretien telescope that is used in many of the large astronomical telescopes is invented by George Ritchey and Henri Chretien.
  • In 1930, The Schmidt camera is created by Bernhard Schmidt.
  • In 1937, Grote Reber developed a telescope for wavelengths ranging from radio to Xrays.
  • In 1944, The Maksutov telescope is designed by Dmitri Maksutov.
  • In 1962, The UK launched an orbiting solar telescope.
  • In 1990, the Hubble Telescope was launched into space.
  • In 2013, the James Webb Space Telescope will be launched and take the place of the Hubble.

And this all started with the polishing of a few stones.

More and newer information on Wikipedia

Tuesday, February 6, 2018

Our Neighbors in Space

Crab Nebula - Photo: Wikipedia
We have a special feeling toward the other planets that circle our sun.  Maybe it’s all the science fiction stories about visiting the moon, Mars and other planets.  But we love to think about those planets that make up what we call “the solar system.” that do what our planet does but do it very differently indeed.  

The planets of our solar system have taken on personalities and mythical appeal in our literature and arts.  It is easy to find artists who render their vision of the planets that make up our society of planets near our sun.  The names of the planets, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune are all from our cultural past being gods from Greek and Roman mythology.  But the solar system is not just made up of these planets.  The solar system is a very busy place indeed.

In 2006, there was quite a bit of controversy as scholars and astronomers agreed to downgrade Pluto and remove its status as a planet.  So you have to wonder, what is it that makes something a planet and what happened to Pluto?  It didn’t just go away so it must still be out there.  A planet, by scientific definition, is any object in orbit around a sun, that has formed into some kind of round object is a planet as long as it has cleared away any other orbiting items around it.  By cleared away, that doesn’t mean it has destroyed all space debris etc.  For example, our planet has not “cleared away” the moon but it has captured it into its own orbit so we classify as a planet.  That’s a relief huh?

There are many objects floating around in our solar system other than the planets we know of.  It’s an interesting piece of trivia that in addition to the planets there are 165 moons orbiting around those nine planets.  Some of those moons are so advanced that some scientists have suspected that they might have supported life at some point.

In addition to the regular planets and moons, there are dwarf planets, asteroid belts and routine visits by comets that create a lot of traffic in our cosmic corner of the universe.  The two known dwarf planets that exist on the outer rim of our solar system are Eries and Ceres.  So when Pluto’s status was changed to be removed from the list of planets, it simply joined those two bodies as dwarf planets but still a solid citizen of the community of celestial bodies around our sun.

In addition to these larger bodies, there is an asteroid belt that exists between Mars and Jupiter that most of the asteroids that we see in our night sky come from.  There is another belt of large objects further out called the Kuiper belt as well as a “bubble” in space called a heliopause and there is a suspected additional belt outside the known solar system called the Oort belt that we think is the origin of a lot of large asteroids and comets that frequent our solar system and come to orbit our sun.

As fascinating as these many celestial bodies who are our neighbors in space is the origin of our solar system.  We have to break it down into simple terms to understand the terms but we know that the early history of the solar system and the universe was one of the great bodies of gas and clouds of matter eventually cooling and heating, exploding and spinning off stars and other massive space giants that became more stars, galaxies and solar systems.  It was from this erratic activity that our sun separated from the gasses and carried with it the material that became our solar system.  The gravity of the sun captured sufficient matter that it began to go through the process of forming, cooling, exploding and separating.  This is what happened as the planets all went through the same process eventually establishing stable orbits and small objects falling into orbit around them.

When you think of how powerful and out of control this process is, it’s amazing to step back and see the beauty of the organization of our solar system today.  The more detail you learn about the history of our solar system, the more you will enjoy your explorations of the planets with your telescope.  That discovery is part of the fun of astronomy.

Wednesday, January 24, 2018

Looking at Globular Clusters

Globular Clusters in NGC 4490 - Photo: Flickr
Globular clusters are defined as a dense grouping of thousands to millions of stars.  They are comprised of young stars at millions of years old to older stars at billions of years old.  The stars in these clusters are usually very tightly bound together.

They are considered deep sky objects.  They are easily found in the night sky in the hours before midnight in the months of April through September.  They appear in your telescope as concentrated patches of gray mist.  The amazing part is the average distance between any of the given stars is between ¾ to 1 ½ light years.  

The most spectacular of all is the NGC 5139.  You can see it with your naked eye because it is three times the moon's diameter.  There are millions of stars that take up your viewfinder.  It is truly a wondrous sight to behold.  If you live in or around North Carolina close to the latitude of +36 degrees, you will be able to spot it easily in the night sky.

Clusters such as these are very common.  In the Milky Way, there are 150 known clusters.  The Andromeda galaxy could have upwards of 500.  The giant elliptical galaxies, such as M87, have as many as 10,000.  The neat thing is the globular clusters contain some of the first stars that were created when time began.  Their origins are still unclear.  

The major part of these clusters is found near the galactic core.  And another large majority lie on the celestial sky side.  Clusters contain a high density of older stars but they are not great locations for planetary systems.  The orbits of the planets become unstable in the dense clusters. These clusters can be dated by viewing the temperature the coolest white dwarf stars are in the group.  Common results say some of these stars are 12.7 billion years old or older.

Saturday, December 30, 2017

The Amazing HUBBLE

English: The Hubble Space Telescope as seen fr...
The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis, flying STS-125, HST Servicing Mission 4.
(Photo credit: 
In the history of modern astronomy, there is probably no one greater leap forward than the building and launch of the space telescope known as the Hubble.  While NASA has had many ups and downs, the launch and continued operation of the Hubble space telescope probably ranks next to the moon landings and the development of the Space Shuttle as one of the greatest space exploration accomplishments of the last hundred years.

An amazing piece of astronomy trivia that few people know is that in truth, only about ten percent of the universe is visible using conventional methods of observation.  For that reason, the Hubble really was a huge leap forward.  That is for the very simple reason that the Hubble can operate outside of the atmosphere of Earth.  Trying to make significant space exploration via telescopes from the terrestrial surface of planet Earth is very difficult.  That very thing that keeps us alive, our own Earth’s atmosphere presents a serious distraction from being able to see deeper and further into space.

The Hubble space telescope was named after the great scientist and visionary Edward Hubble who discovered that the universe was expanding which was explained by what is now known in science as Hubble’s Law.  To truly get a feel for the amazing accomplishment that was achieved with the launch of the Hubble telescope, spend some time on Nasa’s web site dedicated to the project at  There are also a number of sites where you can enjoy some stunning pictures from the Hubble including and

It’s hard to believe how long the Hubble has been orbiting earth and sending back amazing video and pictures of what it is discovering in space.  But the Hubble was actually initially launched on April 25th 1990.  It was the culmination of literally decades of research and construction which began in 1977.  Expectations were high as the orbiting telescope was put in place and actually began to function as it was designed to do.

All was not always perfect with the telescope and the early pictures were disappointing.  After some study NASA discovered that the reason for the early failures was the curvatures of one of the main lenses of the orbiting telescope.

We probably could never have kept this intricate piece of equipment operational as well as we have had we not had the Space Shuttle program to give us a tool to implement repairs and improvements to the Hubble.  In 1993 a new lens was installed on the Hubble which corrected the problem of picture resolution that was noted in the early operation of the telescope.

Two other repair and upgrade mission have been made to the Hubble since it launched, both of them in 1997 to upgrade older equipment and to retrofit the telescope to extend its useful life through 2010.  It’s pretty amazing to think that this scientific and mechanical marvel has been operating now for ten years without maintenance.  We can be assured that plans are in the works for NASA to upgrade or replace parts on the Hubble to extend its useful life even further as that 2010 time frame draws closer.

It is hard to imagine the science of astronomy or the natural quest for greater knowledge of our universe without the Hubble.  While many times those who would not fund space exploration have tried to cut funding for the Hubble, the operation of this telescope is just too important to astronomers and to the scientific well being of mankind and our planet not to continue to use the Hubble, or its next natural successor.  We will always need to have a set of eyes in the sky to watch the universe and discover more of its mysteries.

Wednesday, December 20, 2017

The History of ASTRONOMY

Florinus Astronomy 1705 - Photo: Wikimedia
If you have a passion for stargazing, telescopes, the Hubble and the universe and this thing we call “astronomy”, you are far from alone.  Of course, we know that astronomy is a highly respected science that has produced some of the most amazing accomplishments of the twentieth century.  On top of that, it is a thriving area of fascination and one of the most exciting hobby areas going with thousands of astronomy clubs and tens of thousands of amateur astronomers watching the stars every night just like we do.

But did you know that astronomy is one of the oldest and most respected sciences of them all?  As far back as before the times of Christ, the wise and thinking people of societies of the time were looking at the stars and finding ways to track and chart them.  We who love the hobby of astronomy can chart a proud history of astronomers that tracks across millennia and through virtually every culture in civilization.  So for the sake of having some really good trivia to toss around at astronomy club next week, let’s highlight some of the big moments in the history of astronomy.

For many centuries the science of astronomy was not distinct from the practice of astrology.  For clarity, astronomy is the study of the stars, planets, and the universe with a clear scientific approach.  Astrology is the study of the zodiac signs and how they influence our growth, our personalities and our daily lives.  In modern times, we as people of science discount the astrological side and focus on the astronomy of the heavens.  But they were one study for millennia before the age of science made them separate.

There is historical evidence that astronomy was a recognized science as far back as the Babylonian civilization hundreds of years before Christ.  But the study of the stars was not limited to one country.  There were similar movements going on in China, India, and Ancient Egypt and all over the Arabian Peninsula.  The integration of astronomy and religion is so prevalent that we see it in the Christmas story in which the Magi, Zoroastrian priesthood probably from the equivalent of ancient Syria, followed a star to the Christ child.  These astronomers were also astrologers and it was that mixture that leads them to be part of this historic event.

The first book on astronomy was written by Ptolemy during the Greek empire.  Since that historic publication, the who’s who list of great astronomers charts a path right through the center of modern science including Copernicus, Galileo, Kepler, Sir Issac Newton, Jung, Michelangelo, Benjamin Franklin and more recently even Einstein and Stephen Hawkings would join that noble list.  It seemed that from the Renaissance on to this day, virtually any man or woman of intellect dabbled in astronomy at least somewhat and it has always been considered a sign of the learned to know about the universe and things astronomical.

Astronomy has had an impact on so many areas of our lives that we really don’t recognize.  Many words in our language had their roots in astronomy such as…

* Influenza which comes from the Latin root word for influence.  This reflects an early belief that the position of the moon and stars may influence health and cause or cure disease.

* Disaster which comes from the Latin for “bad star”.

* Lunatic which has the root word "Luna" in it which is the Latin word for moon.  This highlights the long-held belief that is even prevalent today that irrational behavior and even wild and dangerous things happen during a full moon.

Astronomy and its interrelationship with astrology have also influenced culture, education, and religion to a very large extent over the centuries.  In the English language, the first two days or our week, Sunday and Monday are a reference to astronomy as their literal interpretations would be “The Day of the Sun” and “The Day of the Moon.”   

So if you have found astronomy becoming a consuming passion in your thoughts and what fascinates you about the world we live in, you are in great company as this area of study has been a major part of the culture and thought virtually since the dawn of civilization.  And it will continue to fascinate mankind for as long as those beautiful stars shine over our heads.

Friday, December 15, 2017

Comets - Visitors From Beyond.

Comet - Photo: Pixabay
The one thing we love the most in the world of astronomy is a good mystery.  And if there was ever a mysterious and yet very powerful force of nature that we witness in the night skies, it is the coming of the mighty comet.

The arrival of a comet within view of Earth is an event of international importance.  Witness the huge media attention that the Haley or Hale-Bopp have had when they have come within view The sight of these amazing space objects is simultaneously frightening and awe-inspiring.  

Above all, it is during these comet viewings that the astronomer comes out in all of us.  But what is a comet?  Where did it come from?  And how does it get that magnificent tail?

We should never confuse comets with asteroids.  Asteroids are small space rocks that come from an asteroid belt between Mars and Jupiter.  While still quite stunning to see, they pale in comparison to the arrival of a comet.  Asteroids also have received considerable study by the scientific community.  

Not as much is known about comets.  As a rule, comets are considerably larger than asteroids.  The composition of a comet is a mixture of nebulous, gasses, ice, dust and space debris.  One scientist called the composition of a comet as similar to a “dirty snowball” because the composition is so diverse and changeable.  The center or nucleus of a comet is usually quiet solid but the “snowball” materials often create a “cloud” around that nucleus that can become quite large and that extends at great lengths behind the comet as it moves through space.  That trailing plume is what makes up the comet’s magnificent tail that makes it so exciting to watch when a comet comes within view of Earth.

The origins of comets are similarly mysterious.  There are a number of theories about where they come from but it is clear that they originate from outside our solar system, somewhere in deep space.  Some have speculated they are fragments left over from the organization of planets that get loose from whatever gravitational pull and are sent flying across space to eventually get caught up in the gravity of our sun bringing them into our solar system.  

Another theory is that they come from a gaseous cloud called the Oort cloud which is cooling out there after the organization of the sun.  As this space debris cools, it gets organized into one body which then gathers sufficient mass to be attracted into the gravity of our solar system turning into a fast moving comet plummeting toward our sun.  However, because of the strong gravitational orbits of the many planets in our solar system, the comet does not always immediately collide with the sun and often takes on an orbit of its own.  

The life expectancy of comets varies widely.  Scientists refer to a comet that is expected to burn out or impact the sun within two hundred years as a short period comet whereas a long period comet has a life expectancy of over two hundred years.  That may seem long to us as earth dwellers but in terms of stars and planets, this is a very short life as a space object indeed.  

Scientists across the globe have put together some pretty impressive probes to learn more about comets to aid our understanding of these visitors from beyond.  In 1985, for example, the United States put a probe into the path of the comet Giacobini-Zinner which passed through the comet's tail gathering tremendous scientific knowledge about comets.  Then in 1986, an international collation of scientists was able to launch a probe that was able to fly close to Haley’s comet as it passed near Earth and continue the research.

While science fiction writers and tabloid newspapers like to alarm us with the possibility of a comet impacting the earth, scientists who understand the orbits of comets and what changes their paths tell us this is unlikely.  That is good because some comets reach sizes that are as big as a planet so that impact would be devastating.  For now, we can enjoy the fun of seeing comets make their rare visits to our night sky and marvel at the spectacular shows that these visitors from beyond put on when they are visible in the cosmos.

Saturday, November 25, 2017

Viewing Deep Sky Objects and Comets

Cygnus Wall - Photo: Wikipedia
Deep sky objects are usually located outside our solar system.  The listing includes star clusters, nebulae, galaxies, and multiple stars.  There is also a list of 110 objects on Messier's list that you can try to locate.  The key to viewing all these heavenly bodies is to go outside on a really dark night and you must have a large telescope (one which an aperture that is greater than six inches).  Light pollution filters may also help improve your view.

What looks like one star in the sky actually becomes two or three when looking through your telescope.  There is a four-part star in Orion's Nebula.  There are also stars that brighten and dim as you watch them over time.  These are called Variable Stars.

Star clusters are thousands of stars grouped together.  They create a spectacular view when looking through a small telescope.  An example of this is the Pleiades.  This is a group of seven bright stars in the Taurus constellation that can be seen with the naked eye.  But once you view them through the telescope, you will find there are thousands of stars in the cluster.

Large gas and dust clouds in space are called Nebulae.  An emission nebula will produce light where a dark nebula will absorb the light.  They can be a challenge to find.

Galaxies have massive numbers of stars that are held together by gravity and are usually found in clusters.  They come in many shapes and sizes – spiral, barred, elliptical, and sometimes irregular shaped.  They appear as faint, fuzzy patches of dust.  

Comets are fascinating to watch as they travel across the sky.  They develop tails and can change brightness as they get closer to the sun.  Not all comets will look the same either.  They may brighten or darken depending on where in the sky you locate them.

Monday, October 9, 2017

MOON Gazing

Moon Gazing - Photo:
For many of us, our very first experience of learning about the celestial bodies begins when we saw our first full moon in the sky.  It is truly a magnificent view even to the naked eye.  If the night is clear, you can see amazing detail of the lunar surface just star gazing on in your backyard.

Naturally, as you grow in your love of astronomy, you will find many celestial bodies fascinating.  But the moon may always be our first love because is the one far away space object that has the unique distinction of flying close to the earth and upon which man has walked.

Your study of the moon, like anything else, can go from the simple to the very complex.  To gaze at the moon with the naked eye, making yourself familiar with the lunar map will help you pick out the seas, craters and another geographic phenomenon that others have already mapped to make your study more enjoyable.  Moon maps can be had from any astronomy shop or online and they are well worth the investment.

The best time to view the moon, obviously, is at night when there are few clouds and the weather is accommodating for a long and lasting study.  The first quarter yields the greatest detail of study.  And don’t be fooled but the blotting out of part of the moon when it is not in full moon stage.  The phenomenon known as “earthshine” gives you the ability to see the darkened part of the moon with some detail as well, even if the moon is only at quarter or half display.

To kick it up a notch, a good pair of binoculars can do wonders for the detail you will see on the lunar surface.  For best results, get a good wide field in the binocular settings so you can take in the lunar landscape in all its beauty.  And because it is almost impossible to hold the binoculars still for the length of time you will want to gaze at this magnificent body in space, you may want to add to your equipment arsenal a good tripod that you can affix the binoculars to so you can study the moon in comfort and with a stable viewing platform.

Of course, to take your moon worship to the ultimate, stepping your equipment up to a good starter telescope will give you the most stunning detail of the lunar surface.  With each of these upgrades, your knowledge and the depth and scope of what you will be able to see will improve geometrically.  For many amateur astronomers, we sometimes cannot get enough of what we can see on this our closest space object.  

To take it to a natural next level, you may want to take advantage of partnerships with other astronomers or by visiting one of the truly great telescopes that have been set up by professionals who have invested in better techniques for eliminating atmospheric interference to see the moon even better.  The internet can give you access to the Hubble and many of the huge telescopes that are pointed at the moon all the time.  Further, many astronomy clubs are working on ways to combine multiple telescopes, carefully synchronized with computers for the best view of the lunar landscape.

Becoming part of the society of devoted amateur astronomers will give you access to these organized efforts to reach new levels in our ability to study the Earth’s moon.  And it will give you peers and friends who share your passion for astronomy and who can share their experience and areas of expertise as you seek to find where you might look next in the huge night sky, at the moon and beyond it in your quest for knowledge about the seemingly endless universe above us.