Space Objects

Observatory / Course Archives / ASTR 110 Fall 2019 / VanRegenmorter

Mercury

Mercury is the first planet from the sun, as well as the smallest. However, it is not the hottest, despite being closest to the sun. It is a terrestrial planet, with a surface similar to that of the moon's, a dense metallic core, a rocky mantle, and solid crust. It is the fastest orbiting planet, with long days, and short years. Mercury does not have any moons, and no signs of life, since daytime temperatures can reach 430 degrees.

Mercury has difficult holding an atmosphere, as it is often blown away by Solar Winds. Luckily, the same solar winds are also bringing in new gases, radioactive decay, and dust, replacing what was originally blown away. Mercury's surface has many craters formed by asteroids, due to the lack of atmosphere. Every seven years or so, Mercury can be seen from Earth passing across the face of the sun.

Cat's Eye Nebula

The Cat's Eye Nebula, located in the Draco constellation, was one of the first nebulas to be discovered. It lies between the little and big dipper, and is visible to observers between October and May. It is considered to be a fossil remnant of a once living star.

There are eleven or more rings around the eye of the nebula, along with gas jets and knots of gas. The star that exploded to make this nebula likely expulsed material in pulses of 1,500 year intervals. This explains the different dust shells present in the nebula. Each shell is discernable, like an onion. The center star will continue to expand for around 10,000 years. After it runs out of atmosphere, the ejected gas will cool and drift in space.

Helix Nebula

Located in the Hydra constellation, Messier 83 is one of the brightest and nearest barred spirals in the sky. It has a diameter of 55,000 light years, making it roughly half the size of the milky way. Although it is smaller than our galaxy, it is producing stars at a much faster rate. It has an apparent magnitude of 7.5, and can easily be seen in May with binoculars.

The pink clouds of hydrogen gas are areas where new stars are forming. The blue sections are clusters of hot, young stars that have blown away the gas that once surrounded them. The yellow center of the galaxy comes from older stars that are a million years old or more. There has been an abnormally high amount of supernovae events in the last century.