Young Space Explorers: Ask Dr. Cathy

Young Space Explorers

Ask Dr. Cathy

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Questions from Previous Weeks

Where do the names of stars like Betelgeuse and Rigel come from? They sound sort of goofy!

I heard that some day the Sun will explode - is that true?

Why do astronomers put telescopes in space? Isn't that expensive?

Wait, are you saying that X-rays and radio waves are forms of light?

Question: Where do the names of stars like Betelgeuse and Rigel come from? They sound sort of goofy!
Dr. Cathy answers: Many of the bright stars have names that were originally given by the Arabs many centuries ago. For instance, the name of the bright orange star Belegeuse in the constellation Orion comes from the Arabic phrase Yad al-Jauza, which means the "hand of Orion". The name Rigel, which is given to the bright white star in Orion, comes from Al-Rijl, which means "the foot" of Orion. Over the years, the pronunciation of the names got a little messed up.

You can find more Arabic star names on a list put together by the Jordanian Astronomical Society at http://www.jas.org.jo/star.html.
You can also see the stars Betelgeuse and Rigel in the constellation Orion in the night sky right now! Here's what the constellation looks like.
Betelgeuse is the bright star at the top left, while Rigel is the bright star at the bottom right. Orion is a Greek name for "The Hunter", since this constellation looks like a man wearing a belt and sword. (Why does Orion have a Greek name? That's another story!)

Question: I heard that some day the Sun will explode - is that true?
Dr. Cathy answers: We know that the Sun will never explode like a supernova, but it will change as it grows older. That's true for everyone!
The Sun is a very stable and well behaved star. That's very good for us! But over a period of billions of years, it is growing brighter and brighter. In about 5 billion years, the Sun will become much larger and brighter than it is now, and will look red instead of yellowish white. Astronomers call this a "red giant" star. This will happen because the Sun's source of energy, the nuclear reactions which occur deep inside, will start to run out of fuel.

Then the Sun will probably have a giant "burp" and toss off a big glowing ball of gas called a "planetary nebula". The Sun will become much smaller and hotter, much smaller and hotter than it is now. Astronomers call this a "white dwarf" star. We know that these things will happen from our studies of other stars.
By the way, planetary nebulae have nothing to do with planets. To astronomers a few hundred years ago, the roundish nebulae looked a bit like the disks of planets. Other nebulae are more fuzzy and irregular looking.
Here is the "Ring Nebula", one of the most well-known planetary nebulae, which is in the constellation Lyra. See the faint white star right in the middle of the nebula? That is the star which created the ring nebula and is now a white dwarf star.

Question: Why do astronomers put telescopes in space? Isn't that expensive?
Dr. Cathy answers:
There are many big advantages to having some of our telescopes in space. First, the Earth's atmosphere blocks many kinds of light that we need to study, such as ultraviolet light, X-rays, some infrared light and radio waves. These forms of light give us much more information than just visible light can alone.
The Earth's atmosphere also blurs and scatters the light coming from stars and galaxies. Trying to look at the stars through the atmosphere is like trying to look into a murky pond and find the minnows - you can do it but it's not easy! Some space telescopes, such as the Hubble Space Telescope, are designed to take advantage of being above the atmosphere and give very, very detailed images that distinguish stars and galaxies that were just blurry messes before.
Telescopes in space have their limitations too, and they are more expensive to build, launch and operate. So for certain kinds of observations we need space telescopes, and it is worth the extra expense and effort. But for many kinds of observations, astronomers will continue to rely greatly on ground-based telescopes.
This is the Hubble Space Telescope, being held in the shuttle bay for servicing during the second servicing mission in 1997. HST was serviced again during the beginning of March. Among the changes was putting in a new, more advanced camera that should provide us with some more of those great Hubble pictures!

Question: Wait, are you saying that X-rays and radio waves are forms of light?
Dr. Cathy answers:
Yes, they are. Our eyes can see all the colors of the rainbow, which we call visible light, but there is much more that our eyes can't see. We generally talk about the following kinds of light: gamma-rays, X-rays, ultraviolet, visible, infrared, microwave, and radio. We use these various forms of light every day - when we cook food in a microwave oven, listen to the radio, watch TV (the signal is sent by radio waves, and the remote uses infrared light), get a tan (from ultraviolet light), and get X-rays of our teeth!

You can learn about the various kinds of light at the Multiwavelength Astronomy website. There you can also see what various astronomical objects, like the Sun, clusters of stars, and galaxies, look like when they are viewed in different kinds of light. It's very cool!

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YSE Home Library Programs Ask Dr. Cathy! Online Activities Space Displays YSE Team Members NASA IDEAS Contact us!	Questions from Previous Weeks Where do the names of stars like Betelgeuse and Rigel come from? They sound sort of goofy! I heard that some day the Sun will explode - is that true? Why do astronomers put telescopes in space? Isn't that expensive? Wait, are you saying that X-rays and radio waves are forms of light? Question: Where do the names of stars like Betelgeuse and Rigel come from? They sound sort of goofy! Dr. Cathy answers: Many of the bright stars have names that were originally given by the Arabs many centuries ago. For instance, the name of the bright orange star Belegeuse in the constellation Orion comes from the Arabic phrase Yad al-Jauza, which means the "hand of Orion". The name Rigel, which is given to the bright white star in Orion, comes from Al-Rijl, which means "the foot" of Orion. Over the years, the pronunciation of the names got a little messed up.
		You can find more Arabic star names on a list put together by the Jordanian Astronomical Society at http://www.jas.org.jo/star.html. You can also see the stars Betelgeuse and Rigel in the constellation Orion in the night sky right now! Here's what the constellation looks like. Betelgeuse is the bright star at the top left, while Rigel is the bright star at the bottom right. Orion is a Greek name for "The Hunter", since this constellation looks like a man wearing a belt and sword. (Why does Orion have a Greek name? That's another story!)
	Question: I heard that some day the Sun will explode - is that true? Dr. Cathy answers: We know that the Sun will never explode like a supernova, but it will change as it grows older. That's true for everyone! The Sun is a very stable and well behaved star. That's very good for us! But over a period of billions of years, it is growing brighter and brighter. In about 5 billion years, the Sun will become much larger and brighter than it is now, and will look red instead of yellowish white. Astronomers call this a "red giant" star. This will happen because the Sun's source of energy, the nuclear reactions which occur deep inside, will start to run out of fuel.
	Then the Sun will probably have a giant "burp" and toss off a big glowing ball of gas called a "planetary nebula". The Sun will become much smaller and hotter, much smaller and hotter than it is now. Astronomers call this a "white dwarf" star. We know that these things will happen from our studies of other stars. By the way, planetary nebulae have nothing to do with planets. To astronomers a few hundred years ago, the roundish nebulae looked a bit like the disks of planets. Other nebulae are more fuzzy and irregular looking. Here is the "Ring Nebula", one of the most well-known planetary nebulae, which is in the constellation Lyra. See the faint white star right in the middle of the nebula? That is the star which created the ring nebula and is now a white dwarf star.
	Question: Why do astronomers put telescopes in space? Isn't that expensive? Dr. Cathy answers: There are many big advantages to having some of our telescopes in space. First, the Earth's atmosphere blocks many kinds of light that we need to study, such as ultraviolet light, X-rays, some infrared light and radio waves. These forms of light give us much more information than just visible light can alone. The Earth's atmosphere also blurs and scatters the light coming from stars and galaxies. Trying to look at the stars through the atmosphere is like trying to look into a murky pond and find the minnows - you can do it but it's not easy! Some space telescopes, such as the Hubble Space Telescope, are designed to take advantage of being above the atmosphere and give very, very detailed images that distinguish stars and galaxies that were just blurry messes before.
		Telescopes in space have their limitations too, and they are more expensive to build, launch and operate. So for certain kinds of observations we need space telescopes, and it is worth the extra expense and effort. But for many kinds of observations, astronomers will continue to rely greatly on ground-based telescopes. This is the Hubble Space Telescope, being held in the shuttle bay for servicing during the second servicing mission in 1997. HST was serviced again during the beginning of March. Among the changes was putting in a new, more advanced camera that should provide us with some more of those great Hubble pictures!
	Question: Wait, are you saying that X-rays and radio waves are forms of light? Dr. Cathy answers: Yes, they are. Our eyes can see all the colors of the rainbow, which we call visible light, but there is much more that our eyes can't see. We generally talk about the following kinds of light: gamma-rays, X-rays, ultraviolet, visible, infrared, microwave, and radio. We use these various forms of light every day - when we cook food in a microwave oven, listen to the radio, watch TV (the signal is sent by radio waves, and the remote uses infrared light), get a tan (from ultraviolet light), and get X-rays of our teeth! You can learn about the various kinds of light at the Multiwavelength Astronomy website. There you can also see what various astronomical objects, like the Sun, clusters of stars, and galaxies, look like when they are viewed in different kinds of light. It's very cool!
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