Solar eclipse, from space!

Bad Astronomy
The entire universe in blog form
Oct. 19 2010 7:00 AM

Solar eclipse, from space!

For their Picture of the Week last, uh, week, the Solar Dynamics Observatory crew chose a fantastically cool shot: the Moon cutting across the disk of the Sun!

sdo_lunar_transit

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!  

Advertisement

Wow! This phenomenal shot was taken on October 7, 2010, as the new Moon slipped between the Sun and the observatory. SDO is in Earth orbit, circling our planet 36,000 km (22,000 miles) up (technically, that's the distance from the Earth's center). The orbit is tilted so the Earth itself only rarely gets in the observatory's way as it watches the Sun day in and day out.

But every now again, when the celestial objects literally align, the Moon can block the view. From the Earth, the Moon was new, meaning it was near the Sun but not blocking it. But from SDO's point of view the geometry was just right to get this partial eclipse (technically called a transit). I drew a rough diagram to give you an idea of how this worked:

sdo_diagram

This isn't to scale, but should help. You can see SDO and its tilted orbit (seen edge-on, so it looks like a line), allowing it to view the Sun without the Earth's big face getting in the way (from SDO's point of the view, the Earth is about 25° across, the apparent size of a dinner plate held at arm's length). The Moon's orbit is tilted as well, and in this case, it happened to be in the way of SDO's line of sight to the Sun.

The shot itself is amazing. It's false color: the camera was actually viewing the Sun in the far ultraviolet, where the solar magnetic field's churning turmoil can be seen plainly. You can see gigantic loops of hot plasma arcing up over the surface of the Sun and then plunging back down. On the left is a spectacular example of that... mind you, the Sun's disk is about 1.4 million km across -- 860,000 miles. That loop is well over 200,000 km (120,000 miles) high! The Earth would be a dot compared to that.

When the Sun does something, it does it big.

If you want to see more pictures like this, put the SDO Picture of the Week RSS feed into your reader. I already have, and when another amazing shot like this pops up, you can bet I'll write about it.

Tip o' the X-ray specs to Lights in the Dark.



Related posts:

TODAY IN SLATE

Politics

The Irritating Confidante

John Dickerson on Ben Bradlee’s fascinating relationship with John F. Kennedy.

My Father Invented Social Networking at a Girls’ Reform School in the 1930s

Renée Zellweger’s New Face Is Too Real

Sleater-Kinney Was Once America’s Best Rock Band

Can it be again?

The All The President’s Men Scene That Captured Ben Bradlee

Medical Examiner

Is It Better to Be a Hero Like Batman?

Or an altruist like Bruce Wayne?

Technology

Driving in Circles

The autonomous Google car may never actually happen.

The World’s Human Rights Violators Are Signatories on the World’s Human Rights Treaties

How Punctual Are Germans?

  News & Politics
Politics
Oct. 22 2014 12:44 AM We Need More Ben Bradlees His relationship with John F. Kennedy shows what’s missing from today’s Washington journalism.
  Business
Moneybox
Oct. 21 2014 5:57 PM Soda and Fries Have Lost Their Charm for Both Consumers and Investors
  Life
The Vault
Oct. 21 2014 2:23 PM A Data-Packed Map of American Immigration in 1903
  Double X
The XX Factor
Oct. 21 2014 3:03 PM Renée Zellweger’s New Face Is Too Real
  Slate Plus
Behind the Scenes
Oct. 21 2014 1:02 PM Where Are Slate Plus Members From? This Weird Cartogram Explains. A weird-looking cartogram of Slate Plus memberships by state.
  Arts
Brow Beat
Oct. 21 2014 9:42 PM The All The President’s Men Scene That Perfectly Captured Ben Bradlee’s Genius
  Technology
Technology
Oct. 21 2014 11:44 PM Driving in Circles The autonomous Google car may never actually happen.
  Health & Science
Climate Desk
Oct. 21 2014 11:53 AM Taking Research for Granted Texas Republican Lamar Smith continues his crusade against independence in science.
  Sports
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.