A Deeper Glance into Space

Observatory / Course Archives / ASTR 110 Fall 2019 / Adelman

Pluto

Pluto, discovered in 1930, was classified as the ninth planet of our solar system until 2006, when it was reclassified as a dwarf planet because it has not cleared its astronomical neighborhood, the Kuiper Belt. However, Pluto will always have a special place in the hearts of astronomers because of the discovery that there is an icy, heart-shaped region on Pluto's surface, estimated to be 1,600 kilometers across. This was discovered back in 2015 when NASA sent out a spacecraft for their mission New Horizons. This spacecraft had a flyby with Pluto, sending many photos of the dwarf planet back to Earth.

This beloved dwarf planet is located approximately five billion kilometers from the Sun, and it has a diameter of 2,370 kilometers, making it much smaller than even Earth's moon. Pluto is comparable in size to other dwarf planets in its neighborhood, such as Eris. But one intriguing factor that sets Pluto apart from the other dwarf planets is that it has an abnormal relationship with one of its five moons, Charon: this moon is so large that the two almost orbit each other as they go about orbiting the Sun, just as double planets do.

Galaxy NGC 1512

Galaxy NGC 1512 is comparable in size to the Milky Way Galaxy, spanning roughly 70,000 light years across. This barred spiral galaxy can be found in the southern constellation, Horologium, 30 million light years away from our galaxy. Slicing through this galaxy is a faint bar of gas, feeding energy into the heart of the galaxy. This energy is believed to come in part from Galaxy NGC 1512's tiny neighbor, Galaxy NGC 1510, and is encouraging star birth in the central starburst ring. This ring is approximately 2,400 light years wide and is composed of infant star clusters. The color of these newborn star clusters depends on the environment in which they are found: a clean or dusty region. Those found in a clean region are observable in visible and ultraviolet light, causing them to appear a bright blue in color. Those located in a more dusty region are visible only in longer wavelengths such as red or infrared, making them appear redder in color.

Due to the massive size difference between Galaxy NGC 1512 and its neighbor Galaxy NGC 1510, the former is often referred to as the Goliath. In the biblical story, David prevailed against Goliath. Will Galaxy NGC 1510 do the same against its Goliath? Unfortunately, the immense gravitational pull of Galaxy NGC 1512 that is acting on Galaxy NGC 1510 appears to state otherwise: these two galaxies are already in a lengthy merging process.

Nebula NGC 2818

Nebula NGC 2818 is located more than 10,000 light years away in the southern constellation, Pyxis (the compass). Within our galaxy, it is one of the few known planetary nebula located inside an open cluster. The overall age of this open cluster is estimated to be around one billion years old. This is particularly noteworthy because many open clusters do not survive long enough to produce planetary nebula. The angular diameter of the nebula is roughly 50", and the overall angular diameter of the open cluster is 9'.

In the picture above, the colors correspond to what elements are being emitted by this nebula: hydrogen is expressed by green, nitrogen by red, and oxygen by blue. Unfortunately, this nebula is not easily viewed in Grand Rapids, Michigan. This is due to the fact that its orientation in the sky is in the southern hemisphere; the highest it rises in the night sky is in January, where is hangs around 10 degrees above the horizon.