Sucks to be Pluto

The moment I finished the space odyssey, I began getting grief about not including Pluto. Sorry friends, but Pluto is not a planet. Sure it used to be, but it was downgraded. Like most other scientists I have to agree that it doesn’t deserve to be in the same class as bodies like Jupiter and Saturn.

The International Astronomical Union (IAU) is who started the drama around Pluto. They are the big shot organization that controls how we think about space. They are also the ones with the authority to name heavenly objects.

The drama started in January 2005 when Eris (official name: Eris 136199) was discovered. Eris was found orbiting out past Pluto in the Kuiper Belt. It was determined to be 27% more massive than Pluto. NASA started calling Eris the tenth planet and got excited about the high probability of finding more planets, but the IAU had something to say about that.

In August 2006, the IAU held a meeting in Prague and passed Resolution 5A. This resolution established guidelines to determine if something is a planet or a dwarf planet.

To be a planet, an object must:
1. Orbit the sun
2. Be large enough to produce enough gravity to make itself (mostly) round
3. Clear the neighborhood around its orbit

To be a dwarf planet, an object must:
1. Orbit the sun
2. Be large enough to produce enough gravity to make itself (mostly) round
3. Not have cleared the neighborhood of its orbit
4. Not be a satellite (moon)

All other objects (i.e. comets, asteroids, etc) are classified collectively as “Small Solar System Bodies”.

Pluto is tiny (only about 70% the size of our moon), but it is able to meet requirements one and two of being a planet. The problem lies in requirement three. Pluto orbits in the Kuiper Belt (basically the same thing as the asteroid belt, just a little larger. It starts right outside the orbit of Neptune). A true planet would have cleared the belt out of its orbit, but Pluto did not.

Picture from http://www.mathiaspedersen.com/

Just like that, Pluto got its planet card revoked. Our solar system only contains 8 planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune). In Resolution 6A, Pluto was officially named a dwarf planet as well as the prototype for a new variety of trans-Neptunian objects, which (according to Resolution 6B) will be called “Plutonian Objects”.

Now Pluto gets to hang out with the other dwarfs, like Ceres and Eris.

Whatever, I would rather hang out with them anyway!

Robert’s Out of This World Space Odyssey: The Asteroid Belt, Where They Teach You to Hate Dinosaurs

It’s time to say goodbye to the “Earth-like” rocky planets of the inner galaxy and move on to explore the gas giants. If you really were traveling from Mars to Jupiter, you would run into another major component of our galaxy: the asteroid belt.

The asteroid belt (the main belt) is an area of the solar system between the orbits of Mars and Jupiter that contains over 4,000 named asteroids that are just orbiting the sun (there are millions of asteroids total). The vast majority of the asteroids in our solar system can be found in the belt. That’s great and all, but if you don’t know what an asteroid is, then you probably do not care.

An asteroid is basically leftover material from the formation of our solar system about 4.6 billion years ago. Sometimes referred to as minor planets, asteroids are nothing more than pieces of space rock. These rocks are leftover because when Jupiter finished forming, it had such an affect that the material between it and Mars stopped forming as well, leaving us with the asteroid belt.

Asteroids are irregularly shaped and covered in collision marks. They all orbit the sun and even rotate – although it looks more like they are just tumbling along. They vary greatly in size. Ceres is the largest and is roughly 952 kilometers (592 miles) in diameter. This monster asteroid is said to contain 1/3 of the total mass of all asteroids. Others are not even a mile in diameter. The smallest asteroid ever discovered is barely 20 feet across. Some of the larger asteroids have small moons orbiting them. Several pair off (sometimes in groups of three) and orbit each other as they orbit the sun.

Getting through the asteroid belt isn’t a big deal. It is such a large space and the asteroids are typically rather small (in comparison to other things in space). If you took every asteroid in our solar system and put them together, you wouldn’t even be able to make something the size of our moon.

The asteroids within the belt are all unique and are classified into three main categories based on their composition. S-Types (stony) are made up of iron, nickel and silicates, M-Types (metallic) are made of metallic metals (i.e. nickel and iron) and C-Types are made of silicates and clay (these are the most common).

Jupiter is a big boy and has a ginormous gravitational field. As it orbits it is able to alter the belt and send some asteroids flying out of the belt in random directions throughout the galaxy. When an asteroid is sent our direction it is referred to as a near-Earth asteroid. Scientists are always tracking these crazy rocks. A near-Earth asteroid that collided with the Earth is believed to be what killed the dinosaurs.

Robert’s Out of This World Space Odyssey: Mars, Who Earth Would Borrow a Cup of Sugar From

Wave to Earth as we pass by on our way to the next planet: Mars!

On a dark night, with a good idea where to look, you can see Mars from Earth. It will look like a bright red dot in the night sky. The ancient Romans named this planet after their god of war and destruction because of its blood red color.

Mars is Earth’s closest neighbor – only 33,900,000 miles (54,500,000 kilometers) away at its closest. Although not the smallest, Mars is no giant. It is about half the size of Earth. The planet does have a very thin atmosphere that is thick enough to have some clouds and weather patterns. The average temperature on Mars is -80°F (-60°C), but can range from -195°F (-125°C) at the poles to around 70°F (20°C) at the equator. Mars has a similar solar day to Earth that lasts 24 hours 39 minutes 35 seconds long. A year on Mars lasts 687 Earth days and is complete with seasons (thanks to a lovely tilt on the axis).

Just like all of the other rocky planets, Mars is covered with volcanoes, valleys, large continents, rocks, blah, blah, blah. Mars is famous for its color, which it gets from its dirt. The soil on Mars contains lots of iron-rich minerals which provide the lovely rust color. Unlike the other rocky planets, Mars does not have a magnetic field. So if you ever get lost there, don’t bother with a compass.

Accompanying Mars through its cosmic voyage are its two moons (satellites): Phobos and Deimos. Named after the two sons of the god Aries (the Greek version of the god Mars), these two moons are not exactly what you think of when you think of a moon. They are very small (Phobos is the largest with a diameter of 17 miles and then Deimos with a diameter of 9 miles) and irregularly shaped. In space, things become round because gravity pulls of them. These two moons are too small to have their own significant gravitational force. Although still debated, it is believed that these moons were actually asteroids that came a little too close to Mars and got stuck in orbit around the planet.

I would hope that all of you have at least heard about the missions to Mars. The world is very interested in studying our closest neighbor. Finding water on the surface of Mars was a huge deal and hints that life may be possible on this planet.