The Stars in the Sky

I found an article from sciencedaily.com entitled, “Farthest stars in Milky Way might be ripped from another galaxy.” The article explains that the 11 farthest known stars in our galaxy are 300,000 light years away, and that 5 of those may have been “ripped” from a different galaxy called the Sagittarius Dwarf. This galaxy orbits the Milky Way, and has lost much of its mass and stars over time. Scientists have figured out that the gravitational pull of our galaxy is literally tearing the Sagittarius Dwarf apart, and so some of the stars we see in the night sky are actually supposed to belong somewhere else.

The article relates to what we’ve been talking about in class because it explains at least one small part of what we see when we look out into space from Earth. From our point of view on this planet, all the other stars, planets, and other celestial bodies appear to orbit us. However, this is simply an illusion caused by the Earth’s rotation around the sun. From our point of view, the sun and stars appear to rise in the east and set in the west. Rising and setting is an illusion caused by the horizon. When the sun sets, it is no longer visible from our point of view because it has dipped below the horizon—meaning that the Earth is blocking us from seeing it. When it rises, it is no longer blocked by the Earth and we are able to see it again. Every celestial body appears to move at the same speed because of the Earth’s rotation; therefore, if the sun rises with a particular constellation, it sets with that constellation as well.

I thought that this was an interesting, informative article because it explains where a few of the billions of stars that we see in the night sky come from. Looking up at the sky at night is fascinating because space is so mysterious and infinite and there’s still so much that we don’t know about the universe. I thought it was weird that our galaxy could damage another so severely without even trying. It’s not like our galaxy planned to do it; both galaxies simply exist near each other and by chance just happened to have a profound effect on its entire structure. It’s so strange that celestial bodies are constantly interacting with each other like that throughout the universe.

UPDATE: (PERSONAL REFLECTION) I thought that the article was interesting and meaningful because it helped to reinforce some of the things that we learned in class about how celestial bodies appear to move in the sky. It also took what we learned about stars rising and setting one step further and explained exactly where a few of those stars came from, which I thought was interesting. Regardless of how far away these stars are or where exactly they came from, however, they all appear to move at the same speed, since this movement is an illusion caused by the Earth’s rotation, and the Earth rotates at a constant rate.

 

Does the North Star Ever Move?

http://earthsky.org/astronomy-essentials/north-star-movement

Sky wheeling around Polaris, the North Star.

The first conceptual objective, I can explain how astronomical objects (sun, planets, stars) appear to move in the sky, has been discussed frequently in class. In class we discussed that astronomical appear to move in the sky, but in fact, they are positioned. This illusion is caused by Earth’s rotation. The article I chose, “Does the North Star Ever Move?”, closely relates to the conceptual objective 1. Unlike every other star in the sky, the North Star, Polaris, appear to stay fixed in our sky. The time lapse photo shown above of the North Star and its surrounding stars would suggest that Polaris appears to slightly move. This is due to the rotation of Earth. Because the North Star is directly above the northern axis, it does not rise or set. In class, we also talked about certain stars that do not rise or set in the sky, these stars are called circumpolar stars. This article caught me by surprise. Even though the stars are fixed, Earth’s rotation appears to make them move. I was under the assumption that even with Earth’s rotation, the North Star has always stayed in the same location. This article suggests that the North Star, in fact, makes its own little movement around the sky’s north pole. Therefore, this article taught me something I was not aware of previously.

Christopher Stricker