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547
Science, Astronomy, & Physics / Lake Erie froze over, now over 80% of Lake Ontario is too.
« on: February 20, 2015, 06:06:15 PM »
More than 4,700 square miles of ice formed over the Great Lakes in just one night on Tuesday.
The Arctic blast that swept the Midwest and Northeast saw a near-record amount of Lake Ontario was iced over, with just 20 per cent of open water left.
Overall 82 percent of the five water bodies sealed up.
Ice is largely uncommon on Lake Ontario, which normally sees around 11 percent cover.
Particularly deep, it retains heat longer than its neighboring water bodies.
Lake Erie is entirely iced over.
Almost 92 percent of Lake Huron is covered, and 89 percent of Lake Superior.
Michigan remains the most ice-free with 57 percent of cover.
This time last year, 32 percent of Lake Ontario was iced over. Now, over 80% percent of the water is covered, which is the closest to the record of 86 percent since 1979.
A 'Siberian Express' was barreling up from the Southeast to the Midwest and the East Coast bringing 100 record lows across the region on Thursday, according to forecasters.
Kentucky was the first to experience a record-breaking low in the early hours of Thursday when the city of Paducah felt -8F - the coldest temperature in 120 years.
The Arctic blast that swept the Midwest and Northeast saw a near-record amount of Lake Ontario was iced over, with just 20 per cent of open water left.
Overall 82 percent of the five water bodies sealed up.
Ice is largely uncommon on Lake Ontario, which normally sees around 11 percent cover.
Particularly deep, it retains heat longer than its neighboring water bodies.
Lake Erie is entirely iced over.
Almost 92 percent of Lake Huron is covered, and 89 percent of Lake Superior.
Michigan remains the most ice-free with 57 percent of cover.
This time last year, 32 percent of Lake Ontario was iced over. Now, over 80% percent of the water is covered, which is the closest to the record of 86 percent since 1979.
A 'Siberian Express' was barreling up from the Southeast to the Midwest and the East Coast bringing 100 record lows across the region on Thursday, according to forecasters.
Kentucky was the first to experience a record-breaking low in the early hours of Thursday when the city of Paducah felt -8F - the coldest temperature in 120 years.
548
Science, Astronomy, & Physics / 70,000 years ago we had a "near miss" with a star
« on: February 20, 2015, 04:38:57 PM »
Seventy thousand years ago, when humans were migrating from Africa and before Neanderthals became exstinct, an alien star flew through the outer reaches of the solar system.
Passing less than a light-year from Earth, it was the closest stellar near-miss known so far.
Too dim for human eyes to perceive, the small red dwarf may have flared up during its extremely close brush with Earth, making it visible to early humans.
When scientists computed the past orbit "Scholz's star", they found that it came within 0.8 light-years of Earth. That is within the outer reaches of the Oort cloud, a faraway realm populated by trillions of comets.
The Oort cloud is host to an enormous number of comets, some of which visit the inner solar system regularly. But many more of these comets would have come flying towards earth if a passing star-were to approach and perturb the cloud.
A hailstorm of comets could have catastrophic consequences for life on Earth, so astronomers hope to figure out how common these close encounters are. It doesn't look like we have to worry soon. The next closest stellar approach is forecast to be between 240,000 and 470,000 years from now, and should avoid the Oort cloud.
Passing less than a light-year from Earth, it was the closest stellar near-miss known so far.
Too dim for human eyes to perceive, the small red dwarf may have flared up during its extremely close brush with Earth, making it visible to early humans.
When scientists computed the past orbit "Scholz's star", they found that it came within 0.8 light-years of Earth. That is within the outer reaches of the Oort cloud, a faraway realm populated by trillions of comets.
The Oort cloud is host to an enormous number of comets, some of which visit the inner solar system regularly. But many more of these comets would have come flying towards earth if a passing star-were to approach and perturb the cloud.
A hailstorm of comets could have catastrophic consequences for life on Earth, so astronomers hope to figure out how common these close encounters are. It doesn't look like we have to worry soon. The next closest stellar approach is forecast to be between 240,000 and 470,000 years from now, and should avoid the Oort cloud.
549
Science, Astronomy, & Physics / Frost Quakes!
« on: February 20, 2015, 12:18:05 PM »
Residents Mistake 'Frost Quakes' for Airplane Crash, Explosions.
Police dispatchers have been getting calls from residents in Tennessee who believe they're hearing gunfire or exploding gas lines. It turns out they're hearing a winter phenomenon that's uncommon to the region.
"It sounded like an explosion underneath. It moved the floor," one resident told the 911 call center in Spring Hill.
"They say it sounded like a plane hit the building. But it was three different buildings," the caller said, according to WKRN in Nashville.
This cryoseismic activity or booms are sometimes referred to as frost quakes or ice quakes. Water expands when it freezes and stress builds up until it is released.
People often hear this noise more at night because noise during the day tends to drown it out.
"Whenever we get really cold weather, with temperatures around zero, ice or snow on the ground or previous rain event, you'll usually hear this at night," said Bobby Boyd, meteorologist for the National Weather Service in Nashville. "It's just a sudden cracking in the frozen soil or rock that's saturated with ice."
During his 49 years of experience, Boyd said he's been hearing more of this activity this winter, which he attributes it to the record-breaking cold. This winter has been the first time there have been sub-zero degrees Fahrenheit temperatures in Nashville since February 1996.
Boyd, 68, said he is surprised that callers have likened the sound to a loud boom or believed it was an airplane crash.
"It's like an explosion but a muffled boom sound. It's not really loud, at least the ones I heard," Boyd said.
But it was loud enough to wake Boyd up at 4:30 a.m. two nights ago, and clearly audible at 7 p.m. last night.
Boyd said he hasn't heard of a frost quake causing property damage, as it often happens in a relatively shallow part of the ground, but he doesn't rule it out.
"Any movement in the ground where you have frost and freeze, even without the explosion, can cause cracks in sidewalks or heaving in the soil. Winter time is hard on roads and paved areas," he said.
Police dispatchers have been getting calls from residents in Tennessee who believe they're hearing gunfire or exploding gas lines. It turns out they're hearing a winter phenomenon that's uncommon to the region.
"It sounded like an explosion underneath. It moved the floor," one resident told the 911 call center in Spring Hill.
"They say it sounded like a plane hit the building. But it was three different buildings," the caller said, according to WKRN in Nashville.
This cryoseismic activity or booms are sometimes referred to as frost quakes or ice quakes. Water expands when it freezes and stress builds up until it is released.
People often hear this noise more at night because noise during the day tends to drown it out.
"Whenever we get really cold weather, with temperatures around zero, ice or snow on the ground or previous rain event, you'll usually hear this at night," said Bobby Boyd, meteorologist for the National Weather Service in Nashville. "It's just a sudden cracking in the frozen soil or rock that's saturated with ice."
During his 49 years of experience, Boyd said he's been hearing more of this activity this winter, which he attributes it to the record-breaking cold. This winter has been the first time there have been sub-zero degrees Fahrenheit temperatures in Nashville since February 1996.
Boyd, 68, said he is surprised that callers have likened the sound to a loud boom or believed it was an airplane crash.
"It's like an explosion but a muffled boom sound. It's not really loud, at least the ones I heard," Boyd said.
But it was loud enough to wake Boyd up at 4:30 a.m. two nights ago, and clearly audible at 7 p.m. last night.
Boyd said he hasn't heard of a frost quake causing property damage, as it often happens in a relatively shallow part of the ground, but he doesn't rule it out.
"Any movement in the ground where you have frost and freeze, even without the explosion, can cause cracks in sidewalks or heaving in the soil. Winter time is hard on roads and paved areas," he said.
550
Science, Astronomy, & Physics / Closest look at Ceres
« on: February 18, 2015, 05:11:25 PM »
We just had our closest ever look at dwarf planet Ceres in the asteroid belt, & we're about to get a lot closer.
The pair of images, recently captured by NASA's Dawn spacecraft, are something pretty amazing, they're the best photos we've ever taken of the dwarf planet Ceres, in the asteroid belt.
Dawn was launched in 2007 in order to visit Vesta (a large asteroid), then Ceres. It orbited Vesta in 2011, and after a journey of more than three billion miles, in a few weeks, it's scheduled to reach Ceres.
Vesta and Ceres are the two most massive objects in the asteroid belt — the latter is about 38 percent of the surface area of the continental US. Dawn was designed to explore them for the first time.
Vesta is heavily cratered, and rocky, while Ceres is much smoother, and icy. Both of them, however, are rocky bodies that resemble the ones that coalesced to form Earth and the other terrestrial planets in the early days of the solar system — so by studying them, scientists hope, we can learn more about the formation of these planets billions of years ago.
In 2011, Dawn entered Vesta's orbit and stayed there for 14 months. During that time, it took unprecedentedly detailed photos of the asteroid, spotting surface features that could be evidence of liquid water.
The probe also collected geologic data that allowed scientists to map its surface. These observations led scientists to infer that Vesta is different than any other known asteroid: it has differentiated geologic layers, including an iron core. It's believed that in the early days of the Solar System, all other asteroids like this ended up crashing into each other and coalescing to form the inner planets, but somehow, Vesta did not.
Dawn left Vesta's orbit in 2012, and began heading towards Ceres. If the mission is successful, it will be the first to ever orbit two different extraterrestrial objects, which it achieved by using an ion thruster system — an advanced form of propulsion that uses charged particles, rather than conventional propellant, allowing it to change trajectory while consuming much less fuel.
Dawn is now approaching Ceres — it was about 52,000 miles away as of February 12 — and it's projected to begin permanently orbiting it on March 6.
Meanwhile, the New Horizons space probe — which is approaching the most Pluto — is now "encounter phase" of its mission, and it's scheduled to become the first spacecraft to flyby Pluto in July.
Below, Ceres, Vesta, & Comparison:
The pair of images, recently captured by NASA's Dawn spacecraft, are something pretty amazing, they're the best photos we've ever taken of the dwarf planet Ceres, in the asteroid belt.
Dawn was launched in 2007 in order to visit Vesta (a large asteroid), then Ceres. It orbited Vesta in 2011, and after a journey of more than three billion miles, in a few weeks, it's scheduled to reach Ceres.
Vesta and Ceres are the two most massive objects in the asteroid belt — the latter is about 38 percent of the surface area of the continental US. Dawn was designed to explore them for the first time.
Vesta is heavily cratered, and rocky, while Ceres is much smoother, and icy. Both of them, however, are rocky bodies that resemble the ones that coalesced to form Earth and the other terrestrial planets in the early days of the solar system — so by studying them, scientists hope, we can learn more about the formation of these planets billions of years ago.
In 2011, Dawn entered Vesta's orbit and stayed there for 14 months. During that time, it took unprecedentedly detailed photos of the asteroid, spotting surface features that could be evidence of liquid water.
The probe also collected geologic data that allowed scientists to map its surface. These observations led scientists to infer that Vesta is different than any other known asteroid: it has differentiated geologic layers, including an iron core. It's believed that in the early days of the Solar System, all other asteroids like this ended up crashing into each other and coalescing to form the inner planets, but somehow, Vesta did not.
Dawn left Vesta's orbit in 2012, and began heading towards Ceres. If the mission is successful, it will be the first to ever orbit two different extraterrestrial objects, which it achieved by using an ion thruster system — an advanced form of propulsion that uses charged particles, rather than conventional propellant, allowing it to change trajectory while consuming much less fuel.
Dawn is now approaching Ceres — it was about 52,000 miles away as of February 12 — and it's projected to begin permanently orbiting it on March 6.
Meanwhile, the New Horizons space probe — which is approaching the most Pluto — is now "encounter phase" of its mission, and it's scheduled to become the first spacecraft to flyby Pluto in July.
Below, Ceres, Vesta, & Comparison:
551
Science, Astronomy, & Physics / Re: Rosetta's closest comet flyby (pictures)
« on: February 18, 2015, 06:43:13 AM »
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552
Science, Astronomy, & Physics / Re: Rosetta's closest comet flyby (pictures)
« on: February 18, 2015, 06:42:38 AM »
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553
Science, Astronomy, & Physics / Re: Rosetta's closest comet flyby (pictures)
« on: February 18, 2015, 06:41:54 AM »
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