Busy. Please wait.

show password
Forgot Password?

Don't have an account?  Sign up 

Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Don't know
remaining cards
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
restart all cards
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

8Sci CH20

8th Science CH20 Stars and Galaxies

galaxy elliptical, spiral, or irregular shaped groups of stars, dust, and gas held together by gravity and grouped into clusters; Earth belongs to the Milky Way galaxy which contains about 200,000 stars
light-year distance light travels in one year; a light-year is the unit astronomers use to measure distances in space, 1 light-year is about 9.5 trillion kilometers
nebula large cloud of dust and gas whose particles exert a gravitational force on each other, causing the cloud to contract and its internal temperature to rise until fusion betins, resulting in a star being born
star glowing, hot sphere of gas, such as the sun, whose brightness depends on how big and hot it is and its distance from Earth; stars form from nebulas and produce energy by fusion; types of stars include blue supergiants, brown dwarfs, and red giants
sunspot cool, dark areas on the surface of the sun that may appear and disappear over days or months; years in which there are many large sunspots are called sunspot maximums , which occur about every 11 years
supernova explosion of a massive, dense-cored star that occurs when no more material remains in the core to be transformed, resulting in the formation of a small neutron star