Semester APOD Project

Observatory / Course Archives / ASTR 110 Fall 2019 / Rohs

Eris

In 2003 during a Palmer Observatory survey of the outer parts of our solar system, scientists spotted what they thought to be a distant planet even larger than Pluto. This new discovery sparked curiosity in the minds of many scientists, and after further study of the celestial object, it was found to be only slightly smaller than Pluto. This caused scientists to completely rethink what it means to be a planet, and how this new discovery fit into our solar system. The object was eventually given the name Eris, named after the Greek goddess of discord and strife. Eris was eventually classified as being a dwarf planet because it was not massive enough to clear its orbital "neighborhood". Because Pluto also does not meet this requirement, the requirements added to the definition of a planet led to the demotion of Pluto from planet to dwarf planet. To put Eris into perspective, the dwarf planet is about three times farther from the Sun than Pluto, and while it's orbit around the sun would be equal to around 557 Earth years, it's days are very similar in length to ours at about 25.9 hours in a day. When looking at physical qualities, we don't know much about the interior of Eris, but we do know that the surface of the dwarf planet is very cold, ranging in temperatures from around 350 to 410 degrees Fahrenheit. This cold dwarf planet has a rocky structure to its surface, similar to Pluto's. Although the discovery of Eris has made huge changes to the way we look at it our solar system, we still have a lot to learn about this dwarf planet.

The Eagle Nebulae

7,000 light years away in our Milky Way galaxy lies an enormous cloud of interstellar gas and dust. The "Eagle Nebulae", discovered by Jean-Philippe Loys de Chéseaux in 1745, is one of the "most productive regions of active star formation in the night sky." In the pillars of dust where star formation occurs, we see light emitted from the particles excited by the energy of the massive, hot young stars. Ultraviolet light also appears to reveal the dense balls of gas surrounding the stars inside the gas and dust pillars. While these pillars may look fairly small in comparison to the whole nebula, they are actually larger than our whole solar system. The whole Nebula, consisting of many emission nebulae, dark nebulae, and a star cluster, is 70 by 50 light years across. With the right tools, you may see this massive structure in our night sky, just inside the constellation Serpens.

The Whirlpool Galaxy

While we have never seen our own spiral galaxy from an outside perspective, we have been able to see the beautiful spiral structure of the Whirlpool Galaxy. In 1773, Charles Messier stumbled upon a large (160 solar masses) spiral galaxy 23 million light years away in the constellation Canes Venatici. This galaxy is home to an estimated 150 billion stars, all surrounding a supermassive black hole. This structure is similar to our Milky Way, and has allowed astronomers to study the structure and star-forming process of a classic spiral galaxy. When looking at its structure, some astronomers see the nearby galaxy NCG 5195 as the cause for the Whirlpool Galaxy's distinct spiral arms. The colors in the galaxy are a reflection of the stars that live there, red being a sign of the formation of giant stars, while blue shows the young hot stars of the region. Overall the Whirlpool Galaxy is a wonder to see, and a great way to learn more about our own spiral galaxy as well.