An Introduction to Astronomy on the Web


Today we will use the internet to view some astronomy sites. Some of these can be used like a general reference, for topics like the solar system or space exploration, and some of them are concerned with modern research, on topics such as planetary formation and black holes.

Besides giving you an easy (and very picturesque!) place to look for more information about a specific topic, this will also show you a little of the most up-to-date work being done by astronomers today. Perhaps something you see will spark your interest.

So, have fun, take a look at these sites, and on another piece of paper answer the questions (hopefully they will make you think about what you see at each site). There aren't too many particular sites listed in the hopes that you will be curious and follow links to topics that interest you at each site. When you are done, or if you want to know more about a particular topic, try using a search engine to find more information.

University of Michigan Astronomy (
Well, we might as well start with our own University of Michigan astronomy department web page. You can find information about the undergrad/grad students and instructors, and current research projects going on at U of M in astronomy. Professor Gary Bernstein is building a large CCD for telescopes, follow the link to information about his Big Throughput Camera.
1. A CCD is essentially a digital camera. Why would astronomers want to use this rather than their eyes or a photograph?
Professor Bernstein's big CCD camera is special because it is very large compared to most modern CCDs.
2. What are some of the advantages to using a bigger CCD? Can you think of any disadvatanges?

The Nine Planets(
This is a good place to start to look for information about the solar system, it has information on practically everything from the Sun to the Oort Cloud. If you want to know the distance from the sun to Mars, you can find it here. You can also find out about space exploration missions to other planets.
3. Look at the information on Europa. In the science fiction book 2010, life existed on Europa. Lately Europa scientific speculation about life on Europa has started. What conditions on Europa now appear like they may support life?

Windows to the Universe (
This is another good place to look for information about the solar system, and this one extends outside the solar system to give some information about the rest of the universe. This site offers information on beginner, intermediate and advanced levels -- be sure you look at the advanced level (after all you're in a college astronomy class).
4. Enter the site in whatever mode (frames/non-frames) you want, then follow the "Universe" link. If you see anything that interests you, be sure to take a peek. Take a look at the "Strange Stuff" link, and then go to the information about Gamma Ray bursters. The information given says that these objects are uniformly distributed over the sky, but then says that these could be objects very nearby (in the halo of our galaxy) or very far away (in the earliest galaxies ever formed). Why can't astronomers tell which is right?

The Hubble Space Telescope(
This is the homepage of the Space Telescope Science Institute, the managers of the Hubble Space Telescope. For images of things outside the solar system, this is the place to look.
Some of the subjects we will study later in the term include black holes and the Crab Nebula. Try to find images of these things (check out pictures, greatest hits, etc.)
5. When you find an image of a 'black hole', you will notice you don't see a black dot where the black hole might be. What do you see instead? This is because the black hole is surrounded by an 'accretion disk', something we will learn more about later.
6. What do you think is the best thing (either specific observation or general thing) the Hubble Space Telescope has done?

Stars and Constellations (
This is a site where many constellations are listed and illustrated. Later in the term we will have a constellation quiz, so you might find this to be somewhat useful, but it's more interesting for the stories that are included for some of the constellations.
7. Name and draw a constellation that we could see from Ann Arbor at this time of year. Remember, from Ann Arbor, we can only see things in the northern hemisphere. We can't see things near the south pole.

Nasa's Homepage (
This is NASA's homepage. From here you can find information on what projects NASA is currently carrying out (hot topics), the history of past projects, the developing version of the space shuttle, and even what projects NASA would like to fund (maybe you have just the thing they're looking for??)
Go to the Mars Pathfinder information (here). This was a tremendously popular mission that also gave us a lot of useful science results.
8. Explain some things we can learn by sending a probe to a place, that we can't discover from the earth.

Goddard (
Much of NASA's scientific research is carried out at centers throughout the United States. These include the Jet Propulsion Laboratory (JPL) in California and Goddard Space Science Center in Maryland. Goddard manages many astrophysics satellites in space, you can find information on them here. Notice that the Hubble Space Telescope, although the most famous, is certainly not the only useful astronomical satellite. Others well known to astronomers include SOHO, which looks at the atmosphere of the Sun, and the Compton Gamma Ray Observatory, which receives high energy photons (gamma rays) from the universe.
9. We will learn more about the COBE satellite and the cosmic microwave background later in the term. For now, look at the COBE information and tell me what wavelength radiation it receives. Using Wein's law, and the knowledge that the radiation it is looking at is at the peak of a blackbody curve, is the source of the radiation hotter or cooler than the Sun?

Telescope Basics (
People tend to think of optical telescopes whenever they think of astronomy. Of course, there are other kinds of telescopes -- radio telescopes (featured in the movies Contact and Arrival), Xray telescopes, infrared telescopes, telescopes for almost any part of the electromagnetic spectrum. But for amateurs, small optical telescopes is what you use to see the night sky. So, here's some information, including how to determine what 'power' a telescope has.

10. What is the major problem earth-based telescopes face, versus space telescopes? What are some other advantages/disadvantages of earth-based versus space-based telescopes?

Another earth-based telescope is close at hand, at the top of Angell Hall actually. Take a look at its web page ( . Hopefully we'll get some clear nights and be able to observe through this telescope. We can see bright objects from Ann Arbor, but we can't see too many dim ones.
11. Why can't we see dim objects from Ann Arbor? (think of what the night sky around here looks like!).

12. Now you're on your own. Find out something new, astronomy related, from the web (it can be a link from one of the other sites you found here) and tell me about it. Be sure to include the URL where you found it.

13. What did you think of this exercise -- useless, interesting, easy?? And how long did it take you?