When measuring stellar distances, astronomers cannot simply look out into space and judge distance. It’s impossible to use radar to measure these distances due to the star’s gaseous structure, and stars are too far away to send spacecraft to measure the actual distance. In order to measure these distances, astronomers use a process known as the trigonometric parallax. A parallax is the apparent change in location while being viewed from two different locations. This is most easily observed by placing an object, walking 10 feet away, and looking at it. Now move 10 feet to the left and look at the object again. Your brain acknowledges that it was in the same place, but it looks as if it’s in a different location. The trigonometric parallax uses this observation on a much larger scale: as the earth rotates around the sun, the apparent location of distant stars changes. This observation paired with the trigonometric parallax allows us to measure the distance to these stars. By measuring these apparent distances astronomers are able to find out how far away stars are by using the equation d=1/p, where d=distance and p=arcsecs.

When measuring stellar distances, astronomers cannot simply look out into space and judge distance. It’s impossible to use radar to measure these distances due to the star’s gaseous structure, and stars are too far away to send spacecraft to measure the actual distance. In order to measure these distances, astronomers use a process known as the trigonometric parallax.

A parallax is the apparent change in location while being viewed from two different locations. This is most easily observed by placing an object, walking 10 feet away, and looking at it. Now move 10 feet to the left and look at the object again. Your brain acknowledges that it was in the same place, but it looks as if it’s in a different location. The trigonometric parallax uses this observation on a much larger scale: as the earth rotates around the sun, the apparent location of distant stars changes. This observation paired with the trigonometric parallax allows us to measure the distance to these stars.

By measuring these apparent distances astronomers are able to find out how far away stars are by using the equation d=1/p, where d=distance and p=arcsecs.

I have an astronomy exam in about 4 hours, be prepared for articles & explanations of the things I need to know

nationalpost: Gunshot victim undergoes ‘most extensive’ face transplant everSurgeons have detailed what they claim is the world’s most comprehensive face transplant — allowing a 37-year-old man to emerge from behind a mask 15 years after a gun accident almost killed him.Richard Norris of Hillsville, Virginia, was shot in the face in 1997 and lost his nose, lips and most movement in his mouth. Since then, he has had multiple life-saving and reconstructive surgeries but none could repair him to the extent where he felt he could return to society. He wore a prosthetic nose and a mask even when entering hospital for the transplant. (University of Maryland Medical Center/Reuters)

nationalpost:

Gunshot victim undergoes ‘most extensive’ face transplant ever
Surgeons have detailed what they claim is the world’s most comprehensive face transplant — allowing a 37-year-old man to emerge from behind a mask 15 years after a gun accident almost killed him.

Richard Norris of Hillsville, Virginia, was shot in the face in 1997 and lost his nose, lips and most movement in his mouth. Since then, he has had multiple life-saving and reconstructive surgeries but none could repair him to the extent where he felt he could return to society. He wore a prosthetic nose and a mask even when entering hospital for the transplant. (University of Maryland Medical Center/Reuters)

unknownskywalker: ‘Ordinary’ black hole discovered 12 million light years away An international team of scientists have discovered an ‘ordinary’ black hole in the 12 million light year-distant galaxy Centaurus A. This is the first time that a normal-size black hole has been detected away from the immediate vicinity of our own Galaxy. The team used the orbiting Chandra X-ray observatory to make six 100,000-second long exposures of Centaurus A, detecting an object with 50,000 times the X-ray brightness of our Sun. A month later, it had dimmed by more than a factor of 10 and then later by a factor of more than 100, so became undetectable. This behaviour is characteristic of a low mass black hole in a binary system during the final stages of an outburst and is typical of similar black holes in the Milky Way. This detection of a normal black hole so far away for the first time opens up the opportunity to characterise the black hole population of other galaxies. To confirm (or refute) our understanding of the evolution of stars scientists need to search for these objects. If it turns out that black holes are either much rarer or much more common in other galaxies than in our own it would be a big challenge to some of the basic ideas that underpin astronomy. Above: The yellow arrow in the picture identifies the position of the black hole transient inside Centaurus A. The location of the object is coincident with gigantic dust lanes that obscure visible and X-ray light from large regions of Centaurus A. Other interesting X-ray features include the central active nucleus, a powerful jet and a large lobe that covers most of the lower-right of the image. There is also a lot of hot gas. In the image, red indicates low energy, green represents medium energy, and blue represents high energy light.

unknownskywalker:

‘Ordinary’ black hole discovered 12 million light years away

An international team of scientists have discovered an ‘ordinary’ black hole in the 12 million light year-distant galaxy Centaurus A. This is the first time that a normal-size black hole has been detected away from the immediate vicinity of our own Galaxy.

The team used the orbiting Chandra X-ray observatory to make six 100,000-second long exposures of Centaurus A, detecting an object with 50,000 times the X-ray brightness of our Sun. A month later, it had dimmed by more than a factor of 10 and then later by a factor of more than 100, so became undetectable.

This behaviour is characteristic of a low mass black hole in a binary system during the final stages of an outburst and is typical of similar black holes in the Milky Way. This detection of a normal black hole so far away for the first time opens up the opportunity to characterise the black hole population of other galaxies.

To confirm (or refute) our understanding of the evolution of stars scientists need to search for these objects. If it turns out that black holes are either much rarer or much more common in other galaxies than in our own it would be a big challenge to some of the basic ideas that underpin astronomy.

Above: The yellow arrow in the picture identifies the position of the black hole transient inside Centaurus A. The location of the object is coincident with gigantic dust lanes that obscure visible and X-ray light from large regions of Centaurus A. Other interesting X-ray features include the central active nucleus, a powerful jet and a large lobe that covers most of the lower-right of the image. There is also a lot of hot gas. In the image, red indicates low energy, green represents medium energy, and blue represents high energy light.

rhamphotheca: Fossil Discoveries in Scotland Help Fill Crucial Gap in Our Understanding of Land Animals by Tamera Jones A run of recent fossil discoveries in Scotland has helped plug a major 15 million year gap in the fossil record and provide crucial information about the early evolution of land animals. UK palaeontologists led by Professor Jennifer Clack from the University of Cambridge discovered the fossils over a 23-year period. After searching in Devonian-age rocks in Scotland for over 20 years, Clack’s colleague Stanley Wood and Tim Smithson finally chanced upon the fossils. (reconstruction of pedes of various taxa) They include animals both with and without backbones – vertebrates and invertebrates – which lived either in water or on the land between 360 and 345 million years ago. This 15-million-year stretch runs from the end of the Devonian to the early Carboniferous periods. The findings help bridge a puzzling gap in the fossil record between Devonian tetrapods, which were primitive, four-legged, aquatic animals, and the more complex, mostly land-dwelling post-Devonian tetrapods. These more-developed terrestrial animals are essentially our distant ancestors… (read more: Planet Earth)     (top image: Dmitry Bogdanov)

rhamphotheca:

Fossil Discoveries in Scotland Help Fill Crucial Gap in Our Understanding of Land Animals

by Tamera Jones

A run of recent fossil discoveries in Scotland has helped plug a major 15 million year gap in the fossil record and provide crucial information about the early evolution of land animals.

UK palaeontologists led by Professor Jennifer Clack from the University of Cambridge discovered the fossils over a 23-year period. After searching in Devonian-age rocks in Scotland for over 20 years, Clack’s colleague Stanley Wood and Tim Smithson finally chanced upon the fossils.

(reconstruction of pedes of various taxa)

They include animals both with and without backbones – vertebrates and invertebrates – which lived either in water or on the land between 360 and 345 million years ago. This 15-million-year stretch runs from the end of the Devonian to the early Carboniferous periods.

The findings help bridge a puzzling gap in the fossil record between Devonian tetrapods, which were primitive, four-legged, aquatic animals, and the more complex, mostly land-dwelling post-Devonian tetrapods. These more-developed terrestrial animals are essentially our distant ancestors…

(read more: Planet Earth)     (top image: Dmitry Bogdanov)

Study Reveals Why our Ancestors Switched to Bipedal Power

deconversionmovement:

(PhysOrg.com) — Our earliest ancestors may have started walking on two limbs instead of four in a bid to monopolise resources and to carry as much food as possible in one go, researchers have found.

A study published in the journal Current Biology this week, investigated the behaviour of modern-day chimpanzees as they competed for food resources, in an effort to understand why our “hominin”, or “human-like” ancestors became bipedal.

Its findings suggest that chimpanzees switch to moving on two limbs instead of four in situations where they need to monopolize a resource, usually because it may not occur in plentiful supply in their habitat, making it hard for them to predict when they will see it again. Standing on two legs allows them to carry much more in one go because it frees up their hands.

Read More

the-star-stuff: Mercury Surprises: Tiny Planet Has Strange Innards and Active Past Perspective view of ancient volcanic plains in the northern high latitudes of Mercury revealed by NASA’s Messenger spacecraft. Purple colors are low and white is high, spanning a range of about 2.3 km. Width of area spans about 1200 km. Each line is 5 degrees in latitude and longitude. CREDIT: NASA/JHUAPL/CIW-DTM/GSFC/MIT/Brown University

the-star-stuff:

Mercury Surprises: Tiny Planet Has Strange Innards and Active Past

Perspective view of ancient volcanic plains in the northern high latitudes of Mercury revealed by NASA’s Messenger spacecraft. Purple colors are low and white is high, spanning a range of about 2.3 km. Width of area spans about 1200 km. Each line is 5 degrees in latitude and longitude.

CREDIT: NASA/JHUAPL/CIW-DTM/GSFC/MIT/Brown University

the-star-stuff: Earth’s atmosphere has repeatedly been choked in a thick methane haze If you were to visit Earth at most points in its history, it wouldn’t look that different. The continents might be rearranged, but you would still recognize our planet as that familiar pale blue dot. But until about 2.45 billion years ago, Earth was locked in a constant cycle of flipping between clear skies and this hydrocarbon smog. Earth’s atmosphere would have looked much like that of Saturn’s moon Titan, which is also covered in a methane fog. This theory of Earth’s atmospheric past has been around for a while, but it’s only now that an international team of researchers have been able to find definitive proof. By analyzing sediments found in South Africa dating back 2.5 to 2.65 billion years, the team were able to reconstruct the unique atmospheric cycle that then dominated the planet. Writing in Nature Geoscience, they explain the strange push-pull that governed the skies of the early Earth: We find evidence for oxygen production in microbial mats and localized oxygenation of surface waters. Carbon and sulphur isotopes indicate that this oxygen production occurred under a reduced atmosphere that was periodically rich in methane, consistent with the prediction of a hydrocarbon haze. Our simulations predict transitions between two stable atmospheric states, one with organic haze and the other haze-free. The transitions are presumably governed by variations in the amount of biological methane production during the Archaean eon. This cycle likely came to an end with the rise of cyanobacteria, which produced enough oxygen to overwhelm the methane-producing microbes and end the era of hydrocarbon hazes. Still, if you’re looking for a fresh spin on the post-apocalyptic story, how about finding a way to restart this cycle of thick, impenetrable methane smog? Of course, as an LA resident, that just sounds like Tuesday, but I bet others would find it terrifying. Nature Geoscience via ScienceNOW.

the-star-stuff:

Earth’s atmosphere has repeatedly been choked in a thick methane haze

If you were to visit Earth at most points in its history, it wouldn’t look that different. The continents might be rearranged, but you would still recognize our planet as that familiar pale blue dot. But until about 2.45 billion years ago, Earth was locked in a constant cycle of flipping between clear skies and this hydrocarbon smog. Earth’s atmosphere would have looked much like that of Saturn’s moon Titan, which is also covered in a methane fog.

This theory of Earth’s atmospheric past has been around for a while, but it’s only now that an international team of researchers have been able to find definitive proof. By analyzing sediments found in South Africa dating back 2.5 to 2.65 billion years, the team were able to reconstruct the unique atmospheric cycle that then dominated the planet. Writing in Nature Geoscience, they explain the strange push-pull that governed the skies of the early Earth:

We find evidence for oxygen production in microbial mats and localized oxygenation of surface waters. Carbon and sulphur isotopes indicate that this oxygen production occurred under a reduced atmosphere that was periodically rich in methane, consistent with the prediction of a hydrocarbon haze. Our simulations predict transitions between two stable atmospheric states, one with organic haze and the other haze-free. The transitions are presumably governed by variations in the amount of biological methane production during the Archaean eon.

This cycle likely came to an end with the rise of cyanobacteria, which produced enough oxygen to overwhelm the methane-producing microbes and end the era of hydrocarbon hazes. Still, if you’re looking for a fresh spin on the post-apocalyptic story, how about finding a way to restart this cycle of thick, impenetrable methane smog? Of course, as an LA resident, that just sounds like Tuesday, but I bet others would find it terrifying.

Nature Geoscience via ScienceNOW.

unknownskywalker: S249 Region by César Cantú The image shows the Jellyfish Nebula or IC443 to the right, and IC444 to the the left. The first is a planetary nebula which shelters a neutron star, the product of a star that exploded about 30,000 years ago and left a very large remnant; it is located about 5,000 light years away. In the picture the nebulae are flanked by the stars Mu and Etas in the constellation Gemini.

unknownskywalker:

S249 Region by César Cantú

The image shows the Jellyfish Nebula or IC443 to the right, and IC444 to the the left. The first is a planetary nebula which shelters a neutron star, the product of a star that exploded about 30,000 years ago and left a very large remnant; it is located about 5,000 light years away. In the picture the nebulae are flanked by the stars Mu and Etas in the constellation Gemini.

the-star-stuff: How Much Water is On Earth? In this illustration, the blue ball represents the volume of all the water on earth, relative to the size of the earth. The tiny speck to the right of the blue ball represents Earth’s fresh water. CREDIT: David Gallo/WHOI  If Earth was the size of a basketball, all of its water would fit into a ping pong ball. How much water is that? It’s roughly 326 million cubic miles (1.332 billion cubic kilometers), according to a recent study from the U.S. Geological Survey. Some 72 percent of Earth is covered in water, but 97 percent of that is salty ocean water and not suitable for drinking. “There’s not a lot of water on Earth at all,” said David Gallo, an oceanographer at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.

the-star-stuff:

How Much Water is On Earth?

In this illustration, the blue ball represents the volume of all the water on earth, relative to the size of the earth. The tiny speck to the right of the blue ball represents Earth’s fresh water. CREDIT: David Gallo/WHOI 

If Earth was the size of a basketball, all of its water would fit into a ping pong ball.

How much water is that? It’s roughly 326 million cubic miles (1.332 billion cubic kilometers), according to a recent study from the U.S. Geological Survey. Some 72 percent of Earth is covered in water, but 97 percent of that is salty ocean water and not suitable for drinking.

“There’s not a lot of water on Earth at all,” said David Gallo, an oceanographer at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.