Solar eclipse, from space!

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

Meet the New Bosses

How the Republicans would run the Senate.

The Government Is Giving Millions of Dollars in Electric-Car Subsidies to the Wrong Drivers

Scotland Is Just the Beginning. Expect More Political Earthquakes in Europe.

Cheez-Its. Ritz. Triscuits.

Why all cracker names sound alike.

Friends Was the Last Purely Pleasurable Sitcom

The Eye

This Whimsical Driverless Car Imagines Transportation in 2059

Medical Examiner

Did America Get Fat by Drinking Diet Soda?  

A high-profile study points the finger at artificial sweeteners.

The Afghan Town With a Legitimately Good Tourism Pitch

A Futurama Writer on How the Vietnam War Shaped the Series

  News & Politics
Photography
Sept. 21 2014 11:34 PM People’s Climate March in Photos Hundreds of thousands of marchers took to the streets of NYC in the largest climate rally in history.
  Business
Business Insider
Sept. 22 2014 9:39 AM Adrian Peterson Has a Terrible Contract, and Cutting Him Would Save the Vikings a Lot of Money
  Life
The Eye
Sept. 22 2014 9:12 AM What Is This Singaporean Road Sign Trying to Tell Us?
  Double X
The XX Factor
Sept. 19 2014 4:58 PM Steubenville Gets the Lifetime Treatment (And a Cheerleader Erupts Into Flames)
  Slate Plus
Science
Sept. 22 2014 8:08 AM Slate Voice: “Why Is So Much Honey Clover Honey?” Mike Vuolo shares the story of your honey.
  Arts
Television
Sept. 21 2014 9:00 PM Attractive People Being Funny While Doing Amusing and Sometimes Romantic Things Don’t dismiss it. Friends was a truly great show.
  Technology
Future Tense
Sept. 22 2014 7:47 AM Predicting the Future for the U.S. Government The strange but satisfying work of creating the National Intelligence Council’s Global Trends report.
  Health & Science
Bad Astronomy
Sept. 22 2014 5:30 AM MAVEN Arrives at Mars
  Sports
Sports Nut
Sept. 18 2014 11:42 AM Grandmaster Clash One of the most amazing feats in chess history just happened, and no one noticed.