Trish JibbenSmithsonian Astrophysical Observatory

Cambridge,MA

JAXA/SAO/NASA/NAOJ

Astronomy Picture of the Day (February 21, 2007)

What are Stars?

•Balls of gas burning billions of miles away…

SOHO (NASA)

MDI (NASA)

EIT (NASA)

EIT (NASA)

Born

GrowMiddle Age

Old

Born

Grow

Middle Age

Old

Stars change as they get older Just like people

But they changeSlowly…

HST (NASA)

MDI (NASA)

Stars are different sizes

White Dwarf

Stars are Hot!

• The color of a star tells you how hot they are.

Hot Cool

Cool stars are about 5,000 degrees Fahrenheit

Hottest stars can get to be 90,000 degrees

fahrenheit!

Astronomy Picture of the Day July 20, 2006

Some stars are close together

Some stars that look close are really far apartHST (NASA) HST (NASA)

Some are VERY close!

HST (NASA)

Stars are moving!

Stars Rotate

QuickTime™ and aVideo decompressor

are needed to see this picture.

Stars move through space but it takes a longTime to see them move

XRT (JAXA/SAO/NASA/NAOJ)

Why do stars look like dots?

Close up the statue of liberty looks big! If you move away from it. It begins to look smaller…

Hellicopter Airplane

Stars look like small dots because they are very, very, VERY far away.

Space Station

The sun is brightest star in the sky -because we are close.

Because we are so close to the sun the light is really bright and fills the whole sky up with light! Daylight!

SOHO (NASA)

Questions

• What would the sun look like if it were far away?

• What would stars look like if they were close?

• Because the sun is so close we have to use special telescope to see it.

• Because other stars are so far away we have to use telescopes to see them too!