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Observatory / Course Archives / ASTR 110 Fall 2019 / Hubers

Venus

Venus is the second planet from the sun in our solar system. It is known as Earth's "sister planet" due to its similar size, mass, proximity to the sun, and bulk composition. Venus has a mass of 4,867,500,000 quadrillion kg while Earth has a mass 5,972,370,000 quadrillion kg. This means that Venus is roughly 0.9499 the size of Earth and 0.815 as massive. Venus also has a similar interior compared to earth. Both are made up of layers with a core, mantle, and outer crust. Venus has a very slow rotation (243 Earth days per one Venus day). Venus is also very unusual because it orbits backwards and does not have any moons, unlike Earth.

Venus is the hottest planet in our solar system and contains a dense, "hellish" atmosphere that consists of carbon dioxide with clouds of sulfuric acid. From up in space, Venus appears a pretty dull, yellow color. This is likely due to the sulfuric acid in Venus' atmosphere. Venus also has a very active surface that includes volcanic activity that attributes to the dull, yellow color that we see in space. In addition, Venus is also one of the brightest objects in the sky and is easy to spot from the naked eye. Part of this is due to the fact that Venus is surrounded by a very thick cloud bank that is highly reflexive to light. So whenever sunlight hits Venus, it bounces back and we are able to observe Venus as being very bright and easy to see.

Rosette Nebula

The Rosette Nebula is a special type of nebula called an emission nebula. This means that it gives off different colors of light which is why it is so colorful. The cluster and nebula are located in the Milky Way Galaxy and in the constellation Monoceros.This nebula has an open cluster of stars in its center called "NGC 2244." Moreover, NGC 2244 is responsible for steller winds that blow gas outward from the cluster center with very strong winds (roughly 20 km/s). In addition, this nebula is sometimes referred to as "skull", as it resembles a human skull in certain orientations.

Typically, a young star ionizes part of the same cloud where it was born, although only hot, massive stars can release enough energy to ionize the cloud. In this particular nebula, an entire cluster of young stars is doing this work. The color that a nebula emits depends on its chemical composition and ionization levels. The reason the Rosette Nebula appears more red is due to the existence of hydrogen in intersellar gas and its relatively low energy of ionization. The other colors result from different emission lines such as oxygen being shown in green. The blue and yellow spots result from individual stars that are emitting their own light. For instance, the blue spots result from stars inside the cloud that get very hot.

Beehive Cluster

The Beehive Cluster is an open cluster that lies in the constellation of Cancer. It is commonly referred to as "Praesepe" or M44 and was among one of the first objects that Galileo is known to have studied. It is one of the nearest open clusters to earth and contains a very large population of stars (roughly 1,000 stars). From February to May, this cluster is easily visible to the naked eye as a large fuzzy object.This cluster is also estimated to be between 520 and 610 light years from our solar system.

Part of the reason that we can observe so many different stars is because an open cluster are stars that are gravitationally bound and created out of the same star-forming nebulae. It is also discovered that about 68% of the stars in this cluster are M-class (red) dwarfs, 30% are spectral types (F, G, and K), while only 2% are bright, A-class stars which is why we see a variety of colors coming from this cluster. The brightest stars in this cluster appear to be blue-white in color which indicates that these stars are very hot. Furthermore, we can observe mass segregation taking place in this cluster with the more massive stars appearing to "sink" to the center of the cluster while the lighter, less massive stars appear to accumulate around the fringes surrounding the core.