I am titled Melissa.
I've seen 20 revolutions around the sun.
Science + SciFi + Art
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Aspiring amateur astronomer.
Science enthusiast.
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This is what I post.
This is what I look like.
01/24/12
* What I post does not belong to me, unless otherwise stated, obviously. Please don't remove the credit when reblogging.
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The Mileage of Light
Composite Image Credit & Copyright: Dennis L. Mammana
If you’re driving down a dark road on a starry night, you might want to check the odometer. Earlier this month, when traveling astronomer Dennis Mammana did he was greeted with the significant mileage reading of 186,282 miles.
That’s the number of miles light travels in one second. Or, if you prefer kilometers, the number you are looking for is 299,792. Mammana muses that in driving to countless observatories, star parties, and night sky photo shoots it has taken his 1998 vintage sport utility vehicle over 13 years to cover that distance. Of course, he considers his next important mileage milestone to be the distance to the Moon.
Nikon D700
New Research Confirms The Existence of Dark Matter
Image: Don Dixon
Fans of dark matter can rest easy. A study published last month raised eyebrows by suggesting that our cosmic neighbourhood is empty of the extra mass needed to hold the galaxy together. But a re-analysis shows that the dark matter was there all along.
Dark matter is the mysterious, invisible stuff that makes up 83 per cent of the matter in the universe. It is responsible for keeping galaxies from flying apart despite their high spinning speeds, and has aided our understanding of how structures in the universe formed.
The most popular theories say that dark matter is a hitherto undetected particle called a WIMP (weakly interacting massive particle) that is shy of interacting with ordinary matter through any force except gravity.
But several underground detectors waiting for WIMPs have come up empty, or with conflicting results. If the galaxy is so full of dark matter, why hasn’t it shown up yet?
In April, a team led by Christian Moni-Bidin of the University of Concepcion in Chile thought they had a solution: the WIMPs aren’t actually there.
The team tracked the motions of more than 400 stars within 13,000 light years of Earth to estimate the mass of matter – visible and dark – in the sun’s local neighbourhood. They concluded that the mass they found could be explained by the visible matter alone, with no need for dark matter.
But the team made a subtle error, say Jo Bovy and Scott Tremaine of the Institute for Advanced Study in Princeton, New Jersey.
Moni-Bidin and colleagues considered stars whose orbits take them far above or below the Milky Way’s main bright disc, and used the speed at which they orbit the centre of the galaxy to figure out how much of a pull they feel from the nearby mass of stars and dark matter. They assumed that the stars’ speeds would be the same no matter how far they were from the galactic centre. Observations of dust clumps have shown that this assumption is true for young stars orbiting in the galactic disc, which mostly move in a near-perfect circle.
But the stars that orbit high above or far below the disc can’t have circular orbits, Bovy says. The only stars that reach such great heights have been kicked away from the disc by matter in the galaxy’s spiral arms, which sent them on highly elliptical orbits.
Full Article: Crisis averted: Dark matter was there all along
IC 4603
The Turbulent Heart of the Rho Ophiuchi Complex
Copyright: Rolf Wahl Olsen
This image shows the core region of the Rho Ophiuchi Complex, centered around the prominent blue reflection nebula IC 4603. This is one of the nearest star forming regions and the intricacies of the dense interstellar dust clouds in the area provides a spectacular display of light and colours.
The bright star is 7.9 magnitude SAO184376 which is the main source of light for the blue reflection nebula. The contrasting red areas towards the top are primarily due to reflected light from the hearby red giant star Antares, which lies outside the field of view. The entire area is also littered with hundreds of dim reddish stars, which are typically very young T Tauri stars.
Particle Sizes in Saturn’s Rings
In the above image, the color purple indicates regions populated predominantly by ring particles larger than 5 centimeters, while the color green indicates regions with a significant population of small ring particles less than even 1 centimeter.
The white center of Saturn’s B-ring indicates that the density of ring particles was too high to make a good determination. Other radio observations indicate that some ring particles can be as large as several meters across. The impressive nature and clarity of the above sharp image may help determine clues about the origin of Saturn’s beautiful but enigmatic ring system.
Nikon D3100
“These are some of the things hydrogen atoms do, given fifteen billion years of cosmic evolution. It has the sound of epic myth, but it’s simply a description of the evolution of the cosmos as revealed by science in our time. And we, we who embody the local eyes and ears, and thoughts and feelings of the cosmos, we’ve begun at last to wonder about our origins. Star stuff contemplating the stars, organized collections of ten billion billion billion atoms contemplating the evolution of matter, tracing that long path by which it arrived at consciousness here on the planet Earth and, perhaps, throughout the cosmos. Our loyalties are to the species and the planet. We speak for Earth. Our obligation to survive and flourish is owed not just to ourselves, but also to that cosmos, ancient and vast, from which we spring.”
NGC6820 and M27 with FSQ-106ED and Reducer QE 0.73x August 2011 Light Version (by hirocun)
Phases of Planet Venus
The phases of the planet Venus, captured over the time frame of January through May of 2012.
“The Planet Venus, The Roman goddess of love and beauty and the closest planet to us especially now just as it gets closest it will transit across the sun soon. This sequence is a five month transition showing its size continuing to grow and its crescent getting thinner as time progresses.” — Efrain Morales
Moon, Venus, & The Sun
“The Moon and Venus displayed very similar phases yesterday (23 May) almost looking like twins, one heading for the Sun, the other having just performed a remarkable transit wich resulted in the annular eclipse 2 days ago.
The Moon (30’) is still 2 arc minutes smaller than the Sun (32’). The sizes of the 3 bodies are correct but of course not their relative positions. Everything is shot in daylight so I have enhanced the contrast for the Moon and Venus.” — Peter Rosén
