Month: June 2014

A bright idea

Here’s a question for you.  What’s something that’s fundamentally important to how we perceive the world, yet we can’t reach out and touch it, and we can’t hear it?  Light!  You — right now! — are awash in a sea of billions and trillions of particles of light.  Besides rainbows, sunbeams, computer screens, incandescent bulbs, candles, fireflies, and countless more ordinary and extraordinary objects reflecting, refracting, shimmering, glowing, radiating, and emitting the familiar type of light our eyes can see, there are other types of light that our eyes don’t see.  Ever heard of ultra violet or infrared light?  What about x-rays,  gamma rays, micro waves, or radio waves? You can’t see these types of light with your eyes, but there are other ways of perceiving them: anybody who has felt the warmth of a a fire, the heat of a sunburn, or seen x-rays at a doctor’s office has experienced infrared, ultra violet, and x-ray light, respectively.

An astronomer can collect light with her telescope to learn about planets, stars, and galaxies too far to ever visit.  But what is light anyway?  If you want to know, UW astronomy grad student Nicholas Hunt-Walker has the answer!

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Seeing Spots

Do you know what a sunspot is?  They’re regions of magnetic disturbance on the sun the appear darker than their surroundings because they’re a bit cooler.  Sunspots usually appear in pairs with each spot having the opposite magnetic pole of the other.

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See those dark smudges in the middle of the sun in this image?  Yeah, those are sunspots.  They’re constantly appearing, disappearing, and shifting in position on the sun in an 11 year cycle.  Don’t be fooled by how tiny those spots look in that image — sunspots at at least as big as the Earth!

The sun isn’t the only star with spots.  We now know that other stars have starspots of their own.  If you want to know more, UW astronomy grad student Jim Davenport has the scoop on his blog: check it out!

Why no green stars?

Have you ever looked up at the night sky and admired the colors of the stars?  Most stars appear white because they’re too dim to trigger your perception of color, but a few bright stars are bluish, yellowish, orangeish, and reddish! Go outside yourself on the next clear night (a rarity in Seattle, I know, I know…) and check it out!  Or, next time you come to one of our planetarium shows, pay attention to the stellar colors on the dome above you.  The sky is pretty colorful if you know what to look for.

ImageWhy do stars have different colors?  It turns out the color is determined by the star’s temperature.  You’re probably used to thinking of red as a warm color and blue as a cold color, but stellar temperatures work the opposite way: blue stars are the hottest stars and red stars are the coolest stars (though of course still VERY hot!).  So, we’ve got blue, yellow, orange, and red stars, but what about green stars?  Turns out there are no green stars!  Why?  Check out UW Astronomy grad student Eddie Schwieterman’s blog posts for the answer:  No Green Stars part I, and No Green Stars (and no violet stars) part 2.  Then go impress your family and friends with your new knowledge!