Friday, February 25, 2005
This Day:

These great pictures are from the SOlar and Heliospheric Observatory website. This ultraviolet image of the Sun shows a very long filament slanting up roughly at a 45 degree angle across much of the Sun, underneath a long and narrow coronal hole (22 Feb. 2005). Filaments are twisting masses of cooler ("only" 10,000 - 100,000 degrees Kelvin) gas contained by magnetic fields above the Sun's surface in the midst of the much hotter (~ 1,500,000 K) corona. Filaments are called prominences if observed on the Sun's limb or edge.

Ultraviolet Image


H-Alpha Image (Courtesy: SOHO, Click images for Hi-Res)
This particular filament was already there 28 days ago (one solar rotation earlier), as were the two coronal holes. While filaments are fairly common, this one is longer than most that have ever been seen. The filament is particularly well visible in this H-alpha image obtained at the Kanzelhoehe Solar Observatory.
This video shows the filament virtually unchanged for two days. One (looking closely) can detect (around 10:00 UT on Feb. 22) a small coronal mass ejection as it blasts out into space from the lighter, upper active region on the right edge of the Sun.

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2/25/2005   12 comments Post a Comment

12 Comments:

At February 25, 2005 12:08 PM, Anonymous Anonymous said...
I really enjoy this site I must say!
 
At February 25, 2005 12:11 PM, Blogger Sray said...
Komputamuso: Thanks! You are welcome any time, hope to see you again :-).
 
At February 25, 2005 3:17 PM, Blogger Sray said...
Thanks, will try!
 
At February 25, 2005 5:21 PM, Blogger Sray said...
Gindy: Just like sunspots are relatively cool regions of the sun, the filaments are essentially cold regions on the surface of the sun. Normally, the nuclear reaction occurs deep inside the sun, and the heat bubbles up through convection. High magnetic fields around the filaments prohibit a efficient convective transfer of heat, and hence they are cooler. As the sun rotates, the magnetic lines get wrapped around it, and form curved lines, called the filaments. Once the lines get really tight and go once (or more, depending upon the slant) around the sun, they might intersect, thus causing a release of magnetic energy in a big solar flare.
 
At February 25, 2005 7:26 PM, Blogger Sray said...
The earth's magnetosphere protects us from medium sized flares. Larger flares often fries out satellites in orbit. Even larger flares would cause increased UV radiation for a while. It will take a really large (unlikely) eruption to seriously affect the earth. But thankfully, we have a very stable sun here :-).
 
At February 26, 2005 3:24 PM, Blogger Sray said...
"What is an example of an unstable sun? That maybe a wierd question."

Actually, it is not a weird question. There are stars whose outputs flicker quite a bit over periods of years, or even days. But it is hard to imagine such a star harboring life in any of its planets.

Such weirdness results from a) Star is near death and cant maintain its output (red-giant stage, mostly) b) a companion star's gravity creates problems c) a very close planet causes problems.

Also, what if a very large meteorite/wanderer planet/star comes very close to our sun? That would be a problem, as all the planets' orbits might go out of whack!
 
At February 28, 2005 8:15 AM, Blogger Sray said...
I think it is a very real possibility. Even primitive bacteria are life. It might not be that difficult to start life from scratch, given the right conditions, and billions of years. Intelligent life, now that might be extremely rare, as the prerequisite for that is multi-cellular life form, and it took 2 Billion years on earth to jump from single cell to multi-cell.
 
At February 28, 2005 1:20 PM, Blogger Sray said...
Remember that of the 4 billion year old history of life on earth:

a) 2 billion is unicellular
b) 1 billion is simple multi-cellular
c) 500 million is soft-bodied

So, it is 3-4 times more likely that life never went past unicellular on Mars.
 
At March 01, 2005 2:09 PM, Blogger Wayne Smallman said...
Life may have evolved on Earth much sooner than previously estimated.

Recent research has shown life to exist in the permafrost of Siberia.

Also, 80% of biota live in the geosphere -- which is rock strata -- rather than the upper biosphere -- the land, sea and air.

In addition to this, bacterial life has been found as far down as 400 metres beneath the sea floor.

This may well point to life existing at a period on Earth much sooner than anticipated...
 
At March 01, 2005 2:24 PM, Blogger Sray said...
The moon was most likely created when another proto-planet collided with earth (when it was 250 million years old).

It is normally agreed that life started on earth 300-500 million years after that collision (once earth cooled off).

Oldest fossils (Stromatolites) are from 1 billion years after earth was created (about 3.5 Billion years ago).

So life started on earth quite quickly, even after all these cataclysms. So it shouldnt be that rare in the universe, given the right conditions...
 
At March 01, 2005 7:00 PM, Blogger Wayne Smallman said...
It's worth baring in mind that the early Earth was a much more hazardous place than it is now.

For instance, there was much more heavy metal kicking around, like Uranium.

Plus, there was a pressure cooker of poisonous gasses, searing temperatures and lethal ultra-violet rays streaming in through the embryonic atmosphere.

Yet life found a foothold and flourished...
 
At March 01, 2005 7:27 PM, Blogger Sray said...
"Plus, there was a pressure cooker of poisonous gasses, searing temperatures and lethal ultra-violet rays streaming in through the embryonic atmosphere."

There is a theory that life first started near deep-sea vents. There the climate is quite stable (albeit high temperature/pressure), lots of nutrients, high reaction rates, and no UV. Those organisms would be anaerobic, deriving energy from the heat of the vents. Such extreme thermophiles are still found near the vents on earth.
 

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