What is the Purpose of the Spitzer Space Telescope?

There are many different kinds of things to look at in the Universe. There are stars, planets, asteroids, comets, galaxies, black holes, and huge dust clouds. These objects all emit different kinds of light because of their different temperatures. Most stars, like our Sun, are really hot. They emit mainly visible light, and that's why we can see them. Cooler objects, like planets and asteroids, emit mainly infrared light. We can't see this with our eyes, but the new Spitzer Space Telescope can see infrared light (the reason that we can see the planets in our solar system is that they reflect the visible light of our Sun, but we still can't see their infrared light with our eyes). Spitzer can look for newly born planetary systems around other stars in our Milky Way Galaxy by looking for the infrared light they emit.

There are big dust clouds in space that sometimes get in the way of what astronomers are trying to see. Just like clouds on Earth, these clouds in space can cover up what we might want to look at (like when an airplane flies into a cloud on Earth). The reason we can't see through these space clouds is that visible light can't get through them. The good thing about certain types of infrared light is that it goes right through these dust clouds. Since the Spitzer Space Telescope is looking at infrared light, it can see what's on the other side of these huge clouds. The center of our Galaxy is covered by space clouds, and can only been seen by instruments that see in infrared light. In addition, new stars are born in dusty cocoons, and the best way to study them is to use infrared light. Click on the image on the right to see the invisible become "visible" in the infrared.

The Earth's atmosphere lets visible light pass through easily, allowing us to see the Sun during the day and distant stars at night. However, the water vapor in the atmosphere absorbs infrared light from space, and so most infrared light from astronomical objects is blocked by the atmosphere. {Only a very small portion of infrared light reaches us on high mountaintops located in dry environments.} To see most of the infrared light from stars, galaxies and other astronomical objects, we must place a telescope above the atmosphere - typically in space.