Bad Astronomy
The entire universe in blog form
Aug. 13 2009 6:30 AM


Quick! Guess the planet!

Phil Plait Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!  

Saturn with no rings


OK, if you guessed Saturn then a) you're smart, 2) you read the title of this post, c) you read the "alt text" of the image, δ) you saw that bare hint of ring in the corner of the picture, or 5) you had a one in 8 (or possibly 9) chance of getting it right.

But it is Saturn. It's the equinox! This image, taken yesterday, is a raw one from Cassini. In other words, it hasn't been processed to clean up bad pixels and take into account other weirdnesses of the digital detector. So you can't do quantitative science on it, but what you can do is look at it and see how the shadow of the ring on the cloudtops is a thin, thin line. That means the Sun must be shining straight along them, like a tree casting no shadow at noon.

And that is exactly what's going on. The ring particles orbit Saturn exactly above its equator, and that means that if you were standing on Saturn's equator (or floating, I suppose) you'd see the Sun precisely overhead at noon. That's pretty much the definition of "equinox". It's true on Earth, too.

The images are coming in from Cassini fast and steady, and it'll be a few days before they can get all processed and pretty. So for now, check out more raw images from the magnificent machine, and as spring settles in on Saturn's northern hemisphere, we'll see lots more coming from Cassini.



Smash and Grab

Will competitive Senate contests in Kansas and South Dakota lead to more late-breaking races in future elections?

I Am 25. I Don't Work at Facebook. My Doctors Want Me to Freeze My Eggs.

The XX Factor
Oct. 20 2014 6:17 PM I Am 25. I Don't Work at Facebook. My Doctors Want Me to Freeze My Eggs.

Republicans Want the Government to Listen to the American Public on Ebola. That’s a Horrible Idea.

The Most Ingenious Teaching Device Ever Invented

Tom Hanks Has a Short Story in the New Yorker. It’s Not Good.

Brow Beat

Marvel’s Civil War Is a Far-Right Paranoid Fantasy

It’s also a mess. Can the movies do better?

Watching Netflix in Bed. Hanging Bananas. Is There Anything These Hooks Can’t Solve?

The Procedural Rule That Could Prevent Gay Marriage From Reaching SCOTUS Again

  News & Politics
Oct. 20 2014 8:14 PM You Should Be Optimistic About Ebola Don’t panic. Here are all the signs that the U.S. is containing the disease.
Oct. 20 2014 7:23 PM Chipotle’s Magical Burrito Empire Keeps Growing, Might Be Slowing
Oct. 20 2014 3:16 PM The Catholic Church Is Changing, and Celibate Gays Are Leading the Way
  Double X
The XX Factor
Oct. 20 2014 6:17 PM I Am 25. I Don't Work at Facebook. My Doctors Want Me to Freeze My Eggs.
  Slate Plus
Tv Club
Oct. 20 2014 7:15 AM The Slate Doctor Who Podcast: Episode 9 A spoiler-filled discussion of "Flatline."
Brow Beat
Oct. 20 2014 6:32 PM Taylor Swift’s Pro-Gay “Welcome to New York” Takes Her Further Than Ever From Nashville 
Future Tense
Oct. 20 2014 4:59 PM Canadian Town Cancels Outdoor Halloween Because Polar Bears
  Health & Science
Medical Examiner
Oct. 20 2014 11:46 AM Is Anybody Watching My Do-Gooding? The difference between being a hero and being an altruist.
Sports Nut
Oct. 20 2014 5:09 PM Keepaway, on Three. Ready—Break! On his record-breaking touchdown pass, Peyton Manning couldn’t even leave the celebration to chance.