Shop Windows to the Universe

Earth Science Rocks! Select one of our four cool NESTA t-shirts from our online store, and express your love of Earth and space science!
Artist's concept of a rocky planet in orbit around a distant star.
Click on image for full size
NASA, ESA and G. Bacon (STScI)

Planets around other Stars

Did you know that about 200 planets have been discovered around distant stars? The first planet found to be orbiting a star like our Sun was announced in 1995. Since then astronomers have continued to find new planets outside of our solar system, at a rate of more than one new planet every month!

The star and its planet orbit around each other. The planet moves in a wide orbit, while the star just appears to wobble slightly. By measuring the Doppler shift of the light coming from the star, scientists can detect the tiny motion caused by the planet. Most of the distant planets were discovered this way.

If we are lucky, some of the planets can pass in front of their star. This blocks out some of the light that we usually see from the star, briefly making it dimmer. It's like a solar eclipse, but the planet only covers a small part of the star. Only a few planets outside our solar system pass in front of their stars.

All of the distant planets are too far away to see directly. We can only see their effect on the star that they orbit.

Last modified March 13, 2008 by Becca Hatheway.

Shop Windows to the Universe Science Store!

The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

Windows to the Universe Community



You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Solar Eclipses

An eclipse of the Sun occurs when the Earth passes through the Moon's shadow. A total eclipse of the Sun takes place only during a new moon, when the Moon is directly between the Sun and the Earth. When...more

A Newly Discovered Solar System Contains Scaled-Down Versions of Saturn and Jupiter

For a long time, scientists have wondered if there are other systems of planets like our own in our galaxy. Recently a team of astronomers discovered a solar system almost 5,000 light years away that has...more

Small Planet, Small Star

If there are other planets in the Universe that are like Earth, then they might be places where life could survive. However, the search for planets like Earth is not easy. Most of the planets found outside...more


You may have heard of sunspots that sometimes dot the "surface" of the nearest star, our Sun. Well, other stars have spots too. They are called starspots and are relatively cool, dark regions on the visible...more

Magnitude - a measure of brightness

Astronomers use a special term to talk about the brightness of stars. The term is "magnitude". The magnitude scale was invented by the ancient Greeks around 150 B.C. The Greeks put the stars they could...more

Northern Circumpolar Constellations

Because of the rotation of the Earth and its orbit around the Sun, we divide the stars and constellations into two groups. Some stars and constellations never rise nor set, and they are called circumpolar....more

Gamma Ray Bursts - The Most Powerful Objects in the Universe?

In the 1960's, the United States launched some satellites to look for very high energy light, called Gamma Rays. Gamma Rays are produced whenever a nuclear bomb explodes. The satellites found many bursts...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF