Hi Claudia,

Looking for planets outside our solar system used to be considered a silly thing to do. And it depended on a very difficult measurement to make. But a couple of scientists were sure that they could detect such planets if they just kept looking. Finally a couple scientists found very good evidence of planets outside of our solar system (in the 1990s). When that happened, other scientists were intrigued and started looking too. Over a couple of years, it became clear that people really were detecting planets and a lot of scientists started looking. Then NASA and the National Science Foundation (NSF) funded more proposals to look for planets outside our solar system. Now the techniques for looking for planets are becoming more sophisticated and more planets are being found by a lot of scientists.

Laura

Hi Claudia,

I'm not an expert on extra-solar planets, but I will do the best I can to answer your question. The main reasons why scientists are now finding so many planets beyond our solar system are recent advances in technology and our scientific understanding of gravity, planetary motions, and other stars. These planets have probably been there for millions or even billions of years. We just haven't been able to detect them before.

The telescopes that astronomers used in the early part of the 20th century were ground-based telescopes and they were rather small compared to the ground-based telescopes astronomers use today. Having a telescope in orbit like the Hubble Space Telescope also makes it easier to study the motions of far away stars because these motions will not be distorted by our atmosphere. Modern computers and image processing software also help astronomers to search large areas of the sky and study many stars more rapidly than they could in the past.

Even with modern technology, we haven't really been able to directly see extra-solar planets by just looking through a telescope. Most of the discoveries of extra-solar planets have used indirect methods of detecting planets orbiting a star, like variations in the star's brightness or motion.

Kris

Hi Claudia,

Each time we get a better telescope and/or develop new techniques we can look deeper into the universe.
We still can't directly look at a planet outside our solar system, but we can derive that there must be
another planet.

You can ask your teacher to click on 'PlanetQuest Student Activities Guide"at this webpage:
http://planetquest.jpl.na...resources_index.html

Mandy