General Astronomy - Telescopes and Spacecraft

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How far can the Hubble telescope see?

The Hubble Space Telescope can see out to a distance of several billions of light-years. A light-year is the distance that light travels in 1 year. Since light has a speed of 186,000 miles per second (light can travel about 7 times around the entire earth in 1 second!), light travels about 5,865,696,000,000 miles in just one year. You can attach 9 more zeros to the end of this to get 1 billion light-years and another one for 10 billion light-years. The farthest that Hubble has seen so far is about 10-15 billion light-years away. The farthest area looked at is now called the Hubble Deep Field. This area shows a tremendous number of new galaxies, some were so young that they were just being formed. Remember that the farther away an object is from you, the further back in time you see it. For example, our sun is 8 light-minutes away, so it takes light 8 minutes to reach us from the sun and so we see the sun as it was 8 minutes ago. The nearest star, besides the sun, is called Alpha Centauri and is 4.3 light-years away. Thus we see it as it was 4.3 years ago. We are seeing several of the Hubble Deep Field galaxies as they were billions of years ago because this is how long it took for their light to reach us.
How much does the Space Shuttle weigh?
The shuttle weighs 165,000 pounds empty. The external tank weighs 78,100 pounds empty. The two solid rocket boosters weigh 185,000 pounds empty each. But then you have to load in the fuel. Each SRB holds 1.1 million pounds of fuel. The external tank holds 143,000 gallons of liquid oxygen (1,359,000 pounds) and 383,000 gallons of liquid hydrogen (226,000 pounds). The whole vehicle - shuttle, external tank, solid rocket booster casings and all the fuel - has a total weight of 4.4 million pounds at launch. 4.4 million pounds to get 165,000 pounds in orbit is a pretty big difference! To be fair, the shuttle can also carry a 65,000 pound payload (up to 15 x 60 feet in size), but it is still a big difference. The fuel weighs almost 20 times more than the Shuttle.
What tools do astronomers use and what do these tools do?
The main tools used by astronomers are telescopes, spectrographs, spacecrafts, cameras, and computers. Astronomers use many different types of telescopes to observe objects in the Universe. Some are located right here on earth and some are sent into space. Just about everything we know about the Universe comes from the study of the light emitted by objects in space. Astronomers use these tools (especially telescopes) very often. Astronomers also use a lot of physics and mathematics in their work.
 
Telescopes are used to gather light from distant objects and let us see them "up close." Spectrographs break the light up into a "spectrum" which shows us the chemical fingerprints of elements in space and tells us the temperature, composition and velocity of stars, planets, galaxies and nebulae. Cameras are used to gather images. They are connected to telescopes and are placed onboard spacecraft to get pictures of objects in our solar system. Computers are used to analyze the data received from telescopes and spacecraft.
Who took Neil Armstrong's picture when he first set foot on the moon?
The pictures were taken by a camera mounted on the Lunar Module.
What U.S. city had the first planetarium in the western hemisphere?
The Adler planetarium in Chicago, Illinois was the first planetarium built in the western hemisphere. It was constructed in 1930.
How did Johannes Kepler do his calculations of orbital motion without the use the instruments we have available today?
Kepler was a student of Tycho Brahe who used new (at the time) instruments to measure angles and positions of objects in space. There were no telescopes at the time so all of this was done by eye. Tycho gathered a vast amount of data for the time. Kepler used Tycho's data, mathematics, and the concept of force to figure out that planets have elliptical orbits.
How are the distances to objects in space measured?
There are a variety of methods used to determine the distances to objects in space. For close objects, geometric parallax is used. For more distant objects, "standard candles" such as supernovae and Cepheids are used. Standard candles are objects whose real brightness can be closely estimated. By knowing how bright an object really is, and comparing this to how bright it appears from the Earth, we can estimate a distance.

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