phys0001_chapter01

phys0001_chapter01 - Chapter 1 Units in Astronomy We...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 1 Units in Astronomy We introduce the basic measuring units used by astronomers. Length, measured in meter (m), and time, measured in year (yr) or second (s), are familiar to us. The angular size, measured in degrees (°) or arc seconds, which is very important in astronomy, is not commonly used in everyday life. Length Scales Size does matter. The sizes of various astronomical objects are usually so big that we don't have any feeling about them. Here we list the length scales of some typical objects. You can see that, for example, the ratio of the size of our Sun to the size of the Earth is about the ratio of the size of a human to the size of a bee. Length (m) Object > 10 26 Size of the universe 10 26 Distance to quasars 10 24 Size of a typical cluster of galaxies 10 21 Galaxies 10 18 Globular clusters 10 16 Nebula (clumps of gas and dust), light year 10 13 The solar system 10 9 The Sun 10 7 The Earth 10 6 Great Wall 10 2 Buildings 10 0 Basic unit of distance, humans 10 -2 Coins, bees, bugs 10 -4 Diameters of hairs 10 -5
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern