Orion Nebula

The Orion Nebula

Scientific Vocabulary

Accretion: A process where small objects in space collide and stick together to form larger bodies in space.

Fusion: A process in which atoms join together to produce power.

Supernova: A supernova occurs when a supergiant star stops fusion in it's core, collapses then explodes.

Planetesimals: One of the small celestial bodies that were fused together.

How Callisto Formed

There are two ways for a moon to form: accretion and gravity or impact. Jupiter's moon, Callisto formed using accretion and gravity. The Six steps Callisto took towards forming are as follows: First a supernova occurred, then came a nebula. Hot gas and dust left over from the Supernova's explosion swirled around in space. As the cloud cooled atoms started to move slower, therefore clumping together. Then Planetesimals formed and accretion began. Callisto gathered together using the gas and dust that surrounded Jupiter. Then Callisto became a proto Planet and grew to it's full size, however because Callisto did not have enough mass in order to 'clear its neighborhood' of debris. The final step of Callisto's formation was to get caught inside Jupiter's orbit, Where it is even today.

What makes a planet

In order for a planet to be a planet they need to meet the three requirements required by the International Astronomical Union. 1) It needs to orbit around a star. 2) It needs to have enough gravity to pull itself into a spherical shape. 3) It needs to be able to clear its orbit of debris. This makes Pluto, a dwarf planet. Although Pluto has two out of the three characteristics needed in order to be a planet it does not have enough gravitational pull to clear its orbit of debris. My heavenly body, Callisto is a moon and not a planet because it does not revolve around a star, it revolves around Jupiter. Callisto also cannot clear its 'neighborhood' of debris. However Callisto is defiantly big enough to be a planet, Callisto is almost as big as the planet Mercury!


The Dwarf Planet Pluto

Callisto's Size

The moon Callisto is 4,800km in diameter (and 2,403km in Radius). This means that because the Sun's diameter is 1,392,000km in diameter, 290 Callisto's could fit into the sun. If you go to this link
http://ottawa-rasc.ca/kid_space/activities/colouring/colour_jupiter.gif
you can see an artists sketch of the comparison of the moon Callisto, to the planet it orbits, Jupiter. Below is a link to an actual photograph comparing Callisto to Jupiter.
http://upload.wikimedia.org/wikipedia/commons/b/b2/001221_Cassini_Jupiter_%26_Europa_%26_Callisto.jpg

AMNH Experience

On October 26th my grade went to the Museum of Natural History to make observations for our Astronomy unit in Science class. We went to a few rooms in the Museum. One of them was the hall of meteorites. We were able to see three meteorites that have landed on Earth; The Woman, The Dog, and Ahnighito. I learned that each of the three meteorites landed in Cape York, Greenland. I also learned that Ahnighito weighs 200 tons, The Dog weighs 407 kilograms, and The Woman's size is 30 meters. We also went inside the Planetarium, we learned all about our sun ,and how it will eventually burn out. Scientists hope that when our Sun burns out it will not erupt into a supernova. We learned about supernovas in another movie we saw. Supernova's are stars that explode, however when it is a supernova the velocity in which it explodes is very great. When we went into the Rose Center to learn more about our individual body I could not find anything on my moon, Callisto. Fortunately I was able to find some information on the Planet Callisto orbits, Jupiter. I learned that Jupiter's average temperature is -150 Celsius. I also learned that Jupiter is 90% hydrogen and 10% helium. I still want to learn more about Callisto, like how far away it is from our sun and more basic information