Astronomy Picture of the Day 7-18-02

NASA ^ | 7-18-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 July 18

Sunspot Region 30
Credit: MDI, SOHO, ESA, NASA

Explanation: The solar active region designated number 10030 (or simply region 30) is now appearing on the visible hemisphere of the closest star. Dwarfed by the Sun's disk, the group of sunspots which make up region 30 actually cover an enormous area -- nearly 10 times the size of Earth. The panels above were recorded July 15, 16, and 17 (top to bottom) by the MDI instrument on the space-based SOHO Observatory as the solar rotation slowly carried the large, dynamic sunspot group across the Sun's nearside. On July 15, a powerful solar flare erupted from this region followed by a coronal mass ejection. The energetic cloud of electrically charged particles swept past our fair planet yesterday, and as a result enhanced auroral activity is possible.

[petuniasevan]

Astronomy Fun Facts:

Each of those sunspots in the group is much larger in diameter than the Earth.
Their temperature is lower than the rest of the Sun's surface,
but they only appear dark because the surrounding areas are brighter.
If you could isolate a sunspot at the Sun's distance in space,
it would appear to be about 10 times brighter than the full Moon.

Get on the APOD PING list!

[petuniasevan]

APOD PING!

[MeekOneGOP]

Nice pic and interesting info in your note, thanks!
Just a little trivia - I have heard that a lighting bolt is hotter than the
surface of the Sun........

[RightWhale]

a lighting bolt is hotter than the surface of the Sun

The center of a thermonuclear explosion is 10 times hotter than the center of the sun. The acetylene flame on your welding torch is as hot as the surface of the sun.

[MeekOneGOP]

Ah, thanks! More trivia for my limited and challenged memory to grasp
for later, LOL! Thanks! I didn't know that.....

[RightWhale]

More trivia for my limited and challenged memory

Also, a welder's goggles used in arc-welding with one of the darker filters can be used to look at the sun and maybe see one of the larger sunspots. Don't try this with the weaker filters found in cutting torch goggles. Or if you try it anyway, the black spots [a different kind of sunspot] in front of your eyes for the rest of the day or the rest of your life will be a sign that you should remember that somebody said to not do that.

[MeekOneGOP]

I've tried that when I worked for a company that made safety equipment.
We used the welders lenses when there was an eclipse. Not since then, tho!

[petuniasevan]

Whoa! Not seeing much of anything right now. Apparently the APOD NASA site is down.
I'll link you to an image that SOHO made today:

Yes, that's a temperature chart at the bottom. The white outline I'm not sure about.
Maybe it marks the area where a coronal mass ejection would be heading in our general direction. < /wild guess >

[petuniasevan]

Geez, by the time...

Well, in case it goes down again, you have an image.

[Graewoulf]

Is this temperature scale measured in Kelvins?

[Graewoulf]

From these three images, there seems to be evidence of clockwise rotation of portions of the larger area of the sunspot.

Is the clockwise rotation correct?

[petuniasevan]

Yes, those are degrees Kelvin.

For those of you who aren't familiar,
the Kelvin scale is the same as the Celsius temperature scale;
the difference being 0 Kelvin is ABSOLUTE ZERO.

[RightWhale]

I can't tell you anything about sunspots. I know they have positive and negative polarity and occur mainly in pairs. Whether they rotate like huricanes, I can't say.

[ladyinred]

I love these pictures that you post, they are just fasciating and most of them are just beautiful! The little information with it is also very interesting. Thanks!

[RightWhale]

being 0 Kelvin is ABSOLUTE ZERO

Below which there is nothing, end of the scale. It is about 273.16 degrees below zero Celsius. Not that it matters when the object is at 6000 to 9000 degrees.

[Graewoulf]

Thanks for your reply. The "sunspot" is a cooler mass of plasma that eventually sinks into the hotter plasma. Around the edge of the "sunspot" a strong magnetic field develops.

What I saw on the images appeared to be a "tail" of cooler plasma shaped similar to a comma. This suggested to me that the motion was clockwise.

If you know of a movie showing "sunspots" please let me know, as it will be easy to determine the relative direction of spinning from the movie.