The ESA/NASA Solar and Heliospheric Observatory has discovered more than 3000 doomed comets that have passed close to the sun.
The Solar and Heliospheric Observatory, better known as "SOHO", is a joint project of the European Space Agency, or ESA, and NASA. Orbiting the sun at 1.5 million km, or 932,000 miles from Earth, the distant observatory has just discovered its 3000th comet-more than any other spacecraft or astronomer. And, just about all of SOHO's comets have been destroyed.
"They just disintegrate every time we observe one," said Karl Battams, a solar scientist at the Naval Research Labs in Washington, D.C., who has been in charge of running the SOHO comet-sighting website since 2003. "SOHO sees comets that pass very close to the sun-and they just can't stand the intense sunlight."
The overwhelming majority of SOHO's comet discoveries belong to the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet thousands of years ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. On average, a new member of the Kreutz family is discovered every three days. Unfortunately for these small comets, their orbits swoop perilously close to the sun.
There's only one Kreutz comet that made it around the sun – Comet Lovejoy. And we are pretty confident it fell apart a couple of weeks afterwards
Although SOHO's comets are rapidly destroyed, they nevertheless have great scientific value. For instance, the comets' tails are buffeted and guided by the sun's magnetic fields. Watching how the tails bend and swing can tell researchers a great deal about the sun's magnetic field.
Prior to the launch of SOHO in 1995, only a dozen or so comets had ever even been discovered from space, while some 900 had been discovered from the ground since 1761. SOHO has turned the tables on these figures, making itself the greatest comet hunter of all time.
But SOHO hasn't reached this lofty perch alone. The spacecraft relies on people who sift through its data. Anyone can help because SOHO's images are freely available online in real time. Many volunteer amateur astronomers scan the data on a daily basis for signs of a new comet. The result: 95% of SOHO comets have been found by citizen scientists.
Whenever someone spots a comet, they report it to Battams. He goes over the imagery to confirm the sighting and then submits it to the Central Bureau for Astronomical Telegrams, which gives it an official name.
And the name is…you guessed it. "SOHO."
While comets spotted from the ground are named after the person who first discovered them, comets first observed by a space-based telescope are named after the spacecraft. The 3000th comet discovered was named "SOHO-3000."
Naturally, it has already been destroyed. SOHO doesn't mind though. The Greatest Comet Hunter Ever has already moved on to the next sungrazer.
"SOHO-4000," anyone?
Elucidating The Black Holes
"Black holes" is one of the most highly searched terms about our universe. There's a fascination with the idea of a region of space having a gravitational pull so strong, nothing can escape its deadly grasp, not even a sliver of light. Well, not quite. In fact, much of what we think we know about black holes turn out to be myths.
Myth 1 - All black holes are black. As the photograph below from the Event Horizon telescope demonstrated, light can be detected near a black hole's event horizon. This is the boundary between normal space and the space affected by the black hole's gravity, from which no escape is possible. Part of this light comes from the black hole's accretion disk, a flat, pancake like structure composed of dust, gas and other debris. Friction constantly moves the disk's material inward toward the event horizon. Light also comes from jet streams which propel matter outward along the disk's north and south poles.
Myth 2: All black holes are about the same size. Black holes actually come in several different sizes which are defined by their mass. Small black holes are usually the result of a relatively short and violent collapse of a star. Recent work suggests that Intermediate black holes are found in the nuclei of some active galaxies. Super massive black holes on the other hand, are found at the center of nearly every galaxy.
Dr. Dan Evans, an Astrophysicist at NASA Headquarters says, "There's a direct relationship between the beginning of super massive black holes and the beginning of their corresponding galaxy. This strongly suggests the two were born about the same time and slowly grew in size together over billions of years."
Myth 3: If you get within a few thousand miles of a black hole, its super gravity will pull you into its center. It turns out you can get surprisingly close to a black hole. If you approached a black hole with mass equal to our Sun's for example, you could get as close as tens of miles. So imagine if we replaced our sun with a black hole of the same mass. All of the planets would continue to revolve around it, at exactly the same speed and distance as they do now.
Myth 4: Once inside a black hole, nothing ever comes out. Nope. It turns out that radiation can escape from a black hole. One of Stephen Hawking's contributions was a theory that a black hole is not so dense in a quantum mechanical sense. The slow leak of what's now known as Hawking radiation would, over time, cause the black hole to simply evaporate.
The image from the Event Horizon telescope confirmed what Albert Einstein's general theory of relativity predicted over 100 years ago - that a black hole's form is that of a perfect circle. And as scientists learn even more about the properties of this gigantic cosmic mystery we call a black hole, they'll be able to puncture even more myths.
Earth Day Meteor Shower
At the end of a day devoted to Earth, people can look to the heavens for a beautiful shower of Lyrid meteors.
On April 22nd 2015, millions of people around the world will gather together at festivals and other events to celebrate our beautiful blue planet. It's Earth Day, an occasion to pause, reflect, and talk about how to sustain a clean, healthy environment on Earth.
This year, Earth Day will end with a meteor shower.
On April 22-23 ,2015, Earth will pass through a stream of debris from Comet Thatcher, source of the annual Lyrid meteor shower.
As Earth crosses the debris zone, flakes of comet dust, most no bigger than grains of sand, strike Earth's atmosphere traveling 49 km/s (110,000 mph) and disintegrate as streaks of light. Typical Lyrids are about as bright as the stars of the Big Dipper
As meteor showers go, the Lyrids are relatively mild. Most years in April there are no more than 10 to 20 Lyrid meteors per hour. But sometimes, when Earth glides through an unusually dense clump of debris from Comet Thatcher, the rate increases, resulting in what is known as a meteor outburst. Sky watchers in 1982, for instance, counted 90 Lyrids per hour. An even more impressive outburst was documented in 1803 by a journalist in Richmond, Virginia, who wrote:
"Shooting stars [were] observed on Wednesday morning last at Richmond and its vicinity, in a manner that alarmed many, and astonished every person that beheld it. From one until three in the morning, those starry meteors seemed to fall from every point in the heavens, in such numbers as to resemble a shower of sky rockets..."
Another published report from the 19th century lists an observer as having "counted 167 meteors in
about 15 minutes, and could not then number them all.
No such outburst is predicted for 2015-but then again, no outbursts were predicted on those previous occasions either. If you're up late, take a look.
The best time to catch the shower is between about 11 pm on April 22nd and sunrise on April 23rd, in any timezone in the northern hemisphere.
Observing tips: Dress warmly. Bring a reclining chair, or spread a thick blanket over a flat spot of ground. Lie down and look up. Meteors can appear in any part of the sky, although their trails will tend to point back toward the constellation Lyra, from which the meteors get their name. The hours before dawn are best, because that is when Lyra is highest in the sky.
Sometimes, bright moonlight can spoil a meteor shower. That will not be the case on April 22nd. The Moon is just a slender crescent, and it sets shortly after sunset, so lunar glare will not interfere with the Lyrids. If you can, get away from city lights for the darkest possible sky and the best possible show.
Enjoy Earth Day. And then enjoy Earth Night even more.
Enjoying The Geminids From Above And Below
The Geminids meteor shower will be viewed from above by the Meteor camera on the International Space Station, as well as from below by sky watchers on Earth
On the night of December 13, into the morning of December 14, 2018, tune into the night sky for a dazzling display of fireballs. Thanks to the International Space Station, this sky show - the Geminids meteor shower -- will be viewed from both above and below
Sky watchers on the Earth will be sprawled flat on their backs, scanning the skies for fleeting streaks of light or meteors from small particles or meteoroids burning up as they plunge into the atmosphere. While most of those viewers won't be pondering what the shooting stars are made of, astronomers and planetary scientists will be. The Meteor camera on the space station will provide clues.
Meteor records HD video from inside the Window Observational Research Facility (WORF) - looking through thehighest optical-quality window ever installed on a human space vehicle.
This camera helps scientists identify and monitor the activity of meteors, from bolides, extremely bright meteors that typically explode in the atmosphere, to much fainter ones not visible to the naked eye. The camera is equipped with a diffraction grating, an optical component that allows incoming light to be split into selected visible wavelengths of light that are signatures of various elements (Iron, Sodium, Calcium, and Magnesium). By measuring a spectrum or chemical fingerprint from the meteor, the presence of these elements is revealed.
Meteor Science Principal Investigator Tomoko Arai of the Chiba Institute of Technology in Japan says, Our observations focus on annual meteor showers, such as Geminids and Perseids, because their meteoroids originated from known comets or asteroids, so-called meteor showers' parent bodies. The spectral information will tell us the chemical makeup of meteoroids and of their parent bodies. This can help us understand their origin and evolution.
The instrument also helps improve estimates of how much material actually enters Earth's atmosphere. Findings could help mission planners protect spacecraft and Earth from potential collisions with meteoroids.
So what parent body spawns the debris that results in the dazzling Geminids?
Many researchers hypothesize that they are related to a rocky asteroid known as 3200 Phaethon, which passes closer to the sun than any other named asteroid.Phaethon may be a rock-comet-a dormant comet that has accumulated a thick mantle of interplanetary dust grains that can slough off as the comet nears the sun. Phaethon may be an asteroid that was once rich in ice and organics like comets, originally located in the main asteroid belt, which has become active as its orbit has evolved closer to the Sun.
Another possible explanation for the Geminids source is as follows:
There is another object - Apollo asteroid 2005 UD - that seems to be dynamically related to Phaethon and has physical similarities.Some researchers believe that 2005 UD, 3200 Phaethon, and the massive amounts of debris that cause the Geminids are all products of a larger object that has broken apart.
Researchers continue to debate the cosmic drama underlying the Geminids.
Best viewing is Friday morning around 2 AM your local time, after moonset. In the suburbs you could see around 40-50 meteors per hour. Under ideal conditions you could see about 100 meteors per hour! Darker is always better when viewing meteor showers.
