Planets need friends?

Friends are one of the best things in the world and sometimes, when we haven’t seen our friends in awhile, we can get pretty lonely. Did you know that a bunch of planets are considered lonely too? A team of astronomers recently discovered that space is filled with hundreds of billions of these lonely planets, celestial bodies that were kicked out of their original planetary systems.


This came as a surprise to the scientists who had previously believed only about 10 or 20% of stars had planets of this type. In fact, there are 2 Jupiter-sized planets floating around for each of the 200 billion stars in the Milky Way galaxy. This knowledge helps scientists understand more about how such planets form.

In the last 20 years, 500 planets have been identified that are currently circling other stars and this year, scientists announced there are 1,235 more! This information was found using NASA’s Kepler satellite. The lonely planets were found with a method called gravitational microlensing. It uses gravitational fields of massive objects to bend light and act as a magnifying lens.

The light is then monitored for little spots of brightness which are caused by a planet and its host star passing by. Because of the mass of these planets being so close to that of Jupiter, scientists don’t feel there is much chance for life on them. All of this helps scientists understand more about our own solar system and will probably lead to several new theories about planetary formation.

(original image via flickr, with permission to remix)

The Skinny on Pluto

{an artist's creation of the new horizons spacecraft nearing Pluto... image credit via NASA}

Earlier this week on the space log, we talked about the planets in our solar system and how they are arranged in order from the sun. We learned about how something called a mnemonic device can help us remember things. We mentioned that while Pluto was included in our mnemonic, it is actually no longer considered a planet by many astronomers.

Pluto was discovered in 1930 by Clyde Tombaugh. At this time, it was thought to be larger than Earth. After years of studying space and better technologies with which to view things in space, astronomers were able to learn more about Pluto.

Pluto has a strange orbit, even intersecting the orbit of Neptune. It is also smaller than the Earth, not bigger (which Tombaugh originally thought). Pluto has a huge moon nearby, causing some folks to refer to it as a binary planet. When Pluto was first discovered, scientists thought it was alone. In the early 1990s, they started seeing other formations nearby that were almost as big as Pluto itself.

Space scientists from all over the world gathered in 2006 and decided on a formal definition of what a planet is. Pluto was then classified as a “dwarf planet.” Our new list of planets looks like this: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. No Pluto. Can you think of a new mnemonic to remember this list?