Skip to comments.Astronomy Picture of the Day
Posted on 07/04/2008 5:46:20 AM PDT by sig226
Explanation: A new star, likely the brightest supernova in recorded human history, lit up planet Earth's sky in the year 1006 AD. The expanding debris cloud from the stellar explosion, found in the southerly constellation of Lupus, still puts on a cosmic light show across the electromagnetic spectrum. In fact, this composite view includes X-ray data in blue from the Chandra Observatory, optical data in yellowish hues, and radio image data in red. Now known as the SN 1006 supernova remnant, the debris cloud appears to be about 60 light-years across and is understood to represent the remains of a white dwarf star. Part of a binary star system, the compact white dwarf gradually captured material from its companion star. The buildup in mass finally triggered a thermonuclear explosion that destroyed the dwarf star. Because the distance to the supernova remnant is about 7,000 light-years, that explosion actually happened 7,000 years before the light reached Earth in 1006. Shockwaves in the remnant accelerate particles to extreme energies and are thought to be a source of the mysterious cosmic rays.
Yesterday's apod had a copyright notice with a big, fat NO at the source, so I didn't post it. Here's the link if you'd like to take a look.
Fascinating - it has expanded 30 light years from the source in 1000 years .... so what would remain at the source? A neutron star? A dreaded black hole? Anyone want to make a guess, this happy 4th of July??!
Speaking of which (galactic cosmic rays)...
If you look at the chart below, you will see that sunspot activity (during solar maxes--the individual peaks) has been relatively high since about 1900 and almost non-existent for the period between about 1625 and 1725. This period is known as the Maunder (sunspot) Minimum or "Little Ice Age".
From BBC News [yr: 2004]:
"A new  analysis shows that the Sun is more active now than it has been at anytime in the previous 1,000 years. Scientists based at the Institute for Astronomy in Zurich used ice cores from Greenland to construct a picture of our star's activity in the past. They say that over the last century the number of sunspots rose at the same time that the Earth's climate became steadily warmer."..."In particular, it has been noted that between about 1645 and 1715, few sunspots were seen on the Sun's surface. This period is called the Maunder Minimum after the English astronomer who studied it. It coincided with a spell of prolonged cold weather often referred to as the "Little Ice Age". Solar scientists strongly suspect there is a link between the two events - but the exact mechanism remains elusive."
It's really hard to imagine how this little ball of fire could have any impact on our climate at all.
But the main arguments being made for a solar-climate connection is not so much to do with the heat of the Sun but rather with its magnetic cycles. When the Sun is more magnetically active (typically around the peak of the 11 year sunspot cycle --we are a few yrs away at the moment), the Sun's magnetic field is better able to deflect away incoming galactic cosmic rays (highly energetic charged particles coming from outside the solar system). The GCRs are thought to help in the formation of low-level cumulus clouds -the type of clouds that BLOCK sunlight and help cool the Earth. So when the Sun's MF is acting up (not like now), less GCRs reach the Earth's atmosphere, less low level sunlight-blocking clouds form, and more sunlight gets through to warm the Earth's surface...naturally. Clouds are basically made up of tiny water droplets. When minute particles in the atmosphere become ionized by incoming GCRs they become very 'attractive' to water molecules, in a purely chemical sense of the word. The process by which the Sun's increased magnetic field would deflect incoming cosmic rays is very similar to the way magnetic fields steer electrons in a cathode ray tube or electrons and other charged particles around the ring of a subatomic particle accelerator.-ETL
There's a relatively new book out on the subject titled The Chilling Stars. It's written by one of the top scientists advancing the theory (Henrik Svensmark).
And here is the website for the place where he does his research:
2008: "The Center for Sun-Climate Research at the DNSC investigates the connection between variations in the intensity of cosmic rays and climatic changes on Earth. This field of research has been given the name 'cosmoclimatology'"..."Cosmic ray intensities and therefore cloudiness keep changing because the Sun's magnetic field varies in its ability to repel cosmic rays coming from the Galaxy, before they can reach the Earth." :
100,000-Year Climate Pattern Linked To Sun's Magnetic Cycles:
ScienceDaily (Jun. 7, 2002) HANOVER, N.H.
Thanks to new calculations by a Dartmouth geochemist, scientists are now looking at the earth's climate history in a new light. Mukul Sharma, Assistant Professor of Earth Sciences at Dartmouth, examined existing sets of geophysical data and noticed something remarkable: the sun's magnetic activity is varying in 100,000-year cycles, a much longer time span than previously thought, and this solar activity, in turn, may likely cause the 100,000-year climate cycles on earth. This research helps scientists understand past climate trends and prepare for future ones.
Hope you enjoy them...
Wisps Surrounding the Horsehead Nebula:
Carina Nebula Panorama from Hubble:
Bullet Pillars in Orion:
The Rosette Nebula:
For individual descriptions of these images, go to the APOD archive page and run a search on the selected image's title:
On average . . . how many of the Hubble photos posted hereon are natural colors?
Thanks. Much appreciated.
None. The colors have to be reconstructed from multispectral data. Come to think of it, this could also be said of color photography. Natural colors must be seen directly by the eye, not by looking at some artist's impression.
Thanks. That was a very informative link above. I encourage folks to read through the whole thing. Excellen explanation and examples.
A composite image is made of several exposures stacked on top of each other. It enhances the colors.
Hubble image of the same thing:
This was created using different black and white exposures which were filtered to collect light in different colors. The colors were replaced when the image was assembled.
But the colors we see in these photos ARE actual colors being emitted by the objects (assuming it’s an optical light image, as opposed to infrared, ultra-violet, microwave, gamma, x-ray, etc, none of which we can ‘see’ with our eyes of course), it’s just that our eyes are most sensitive to the greenish gray color you referred to in that first Ring Nebula image. In order to see these other sorts of images, the various invisible-to-us wavelengths need to be converted into visible frequencies, or ‘colors’.
Beautiful image in today’s APOD, and thanks for the link to yesterday’s posting...
Never heard of a ‘hoodoo’ before — it made me think of that riff from the flick, “The Bachelor and The Bobby-Soxer”.
They are the real colors, but I chose this to illustrate the methods used to add false colors. Black and white images filtered for specific infrared, ultraviolet, or x-ray frequencies are falsely colored and layered the same way.
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