Distance of Stars

The stars we see in the sky seem bright and twinkling, but how far away could these stars be? An article on universetoday.com called “Closest Star to the Sun” explains how scientists use parallax to measure the distance to stars. To explain parallax, the article says to hold one of your arms out at length and put your thumb up so that it’s beside some distant reference object. Then to take turns opening and closing each eye. They want you to notice how your thumb seems to jump back and forth as you switch eyes. They measure stars by taking the angle of it at one time of year, when the earth is on one side of orbit, and then six months later the other angle. One of the closest stars to our sun is the third brightest star Alpha Centauri. This “star” is actually a cluster of stars formed by Alpha Centauri A, Alpha Centauri B, and Proxima Centauri. Although this star is only visible in the southern hemisphere. The Northern Hemisphere, the closest visible star is Barnard’s Star. To find the mass and size of a star, that requires more of a mathematical equation. If the star’s luminosity and temperature is known, then size and mass can be found.

In our lecture tutorials on page 41-42 we answered questions on parallax angles and measuring distance of stars. When you measure the parallax angle of a star, it won’t tell you directly how far the star is, but give an idea of how far they might be. Parallax angles are measured in arc seconds. A star’s parallax angle is half the angular separation between end points of a star’s angular motion. On page 43 of our lecture tutorial, there are many pictures of the same section of sky throughout a year. We had to determine which star was exhibiting parallax and what the distance from us that it was. I can connect this article back to our conceptual objective 11 I can explain how astronomers study the properties of stars including: distance, size and mass because it explains how scientists use the parallax method to measure the distance of stars. It even gives some examples of close stars to our own star the sun.

I enjoyed reading this article because I feel like it gave me a better understanding of how astronomers measure the distance of stars. It connected to what we learned in class and how we measured parallax using our lecture tutorials. The explanation of parallax was exactly like the demonstration we did in class with our fingers.

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