Astronomers may have located the origin of the Quadrantids
Philip Ball, Nature (translation: Dikla Oren)
Look up, as the year changes, astronomers say - you may see the Quadrantids.
The meteor shower has been lighting up the early January sky since at least 1825. Now astronomer Peter Jenniskens of the SETI Institute in Mountain View, California, may have found the source of the shooting stars. The Quadrantids may be remnants of a celestial object, called 2003 1EH, Jenniskens says. Previously, it was thought that 1EH, discovered in March, is an asteroid, moving in an orbit close to Earth.
Janiskens believes that this object is actually a comet that lost its power. He suggests that it broke up about 500 years ago and released some dust grains, which hit the Earth's atmosphere, burn up and create the nightly display of the Quadrantids.
Most other meteor showers, such as the Leonids in November, also flare up as Earth periodically passes through the dusty remnants of a comet. The dust trail renews itself each time it returns to the inner part of the solar system, so the annual meteor showers become more and more spectacular.
The Quadrantids, which for the most part are relatively weak, appear to arise from the constellation "Bo�tes" in the neighborhood of the "Big Deeper" (a group of seven stars in the constellation Ursa Major). Best visibility is from the Northern Hemisphere from about 11 GMT. The peak of the show usually comes on January 2-4.
Astronomers have known for a long time that the origin of these meteors is in some kind of object, although they have not been able to reach an agreement on the identity of this object. From observing the paths of the meteors, Janiskens calculated the trajectory of this object and found that it matches the trajectory of the 1EH 2003 very precisely.
Astronomers estimate that 2003 1EH itself may be the remnants of a larger comet, called 1490C 1Y. In 1979, the Japanese astronomer Ishiro Segawa discovered that the Quadrantids orbit looks similar to the 1490C 1Y orbit, which is mentioned in the historical records of East Asia from around 1490, and disintegrated about a century later.
Jenniskens joined Brian Marsden of the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, to see if the predicted orbit of 1EH could be matched to that of 1490C 1Y around the time it broke up. This is not a simple task, since the orbits of the comets may have been diverted by approaching the Earth or Jupiter.
The researchers concluded that 2003 1EH may be the ancient core of 14990C 1Y, but the evidence for this is weak. They need better observations of 2003 1EH's current orbit. However, if it turns out that 2003 1EH is indeed the core of a lost comet, it will become a tempting target for future space missions.
The last witnesses to the Father Comet may have been 15th century Chinese astronomers
By Kenneth Chang New York Times, "Haaretz"
Space / What is the origin of the Quadrantid meteors, which will pass near the Earth at the beginning of next week
Next Sunday the meteors known as the Quadrantids will make their annual appearance in the Earth's sky. An American astronomer recently claimed that he was finally able to discover the origin of these meteors.
A meteor is the phenomenon seen when a grain of dust enters the Earth's atmosphere at a speed of several tens of kilometers per second. At such a speed, the dust grain collides with the air molecules, heats up and burns at an altitude of about 100 kilometers. This violent event causes the electrons to be torn from the air molecules, a phenomenon called ionization. The ionized air emits light in a process similar to that of a fluorescent lamp. The emission of light appears to us as a meteor.
The origin of most dust particles is comets - lumps of ice and rock that circle the sun in elliptical orbits. When the comets pass near the Sun, they emit large amounts of dust and ice grains, which continue to move in "swarms", in a path similar to that of the parent comet, for hundreds of years. Comet Temple Tuttle, for example, is responsible for the Leonid meteors, and the origin of the Perseid meteors is in Comet Swift-Tuttle. However, the comet responsible for the Quadrantid meteors is unknown.
Dr. Peter Jenniskens, an astronomer from the SETI Institute in California, noticed that the orbit of 2003 EH1 - a small asteroid discovered in March of this year - is close to the orbit of the Quadrantids. He claims that this is the source of meteors and that it has not been discovered until now because it is dark. According to him, the asteroid is the core of a comet - what remains of it after the evaporation of the ice; The diameter of the asteroid, he estimates, is about three kilometers, "a typical diameter of the core of a comet".
The Quadrantids were discovered in the middle of the 19th century and were named after the constellation Quadrans Moralis, which to the viewer seemed to emerge from. Until now, the Machholtz comet, discovered in 1986, is considered the best candidate for the title of Father of the Quadrantids. But Machholtz's course is different from that of the Quadrantids. While it is not impossible that Jupiter's gravity pulled the comet away from the Quadrantids, no researcher has been able to convincingly show that there is a connection between the two, so scientists continue to look for another source.
Historical astronomical records may indicate the place and time when the comet from which the Quadrantids were ejected was last seen. Between December 31, 1490 and February 12, 1491, Chinese, Japanese, and Korean astronomers observed an exceptionally bright comet passing across the sky. This comet was not seen before that date nor after it.
Dr. Ichiro Hasegawa, a Japanese astronomer, showed a few years ago that the orbit of the comet is similar to the orbit of the Quadrantids. In his estimation, what the 15th century Asian astronomers saw was the disintegration of comet 2003 EH1. This could explain why the comet appeared very bright then and has not been observed since.
Contemporary observations of the Quadrandite meteors also indicate the possibility that they separated from their parent comet only in the last few hundred years.
For example, the trajectory of the meteors comes close to Jupiter, and some close encounters with the planet would cause them to scatter. But according to images taken by a Dutch amateur astronomer in 1995, the Quadrantids, which comprise about five trillion kilograms of rock and dust, are still close together, indicating that they have yet to pass by Jupiter many times. Indeed, according to Dr. Janiskens' calculations, the quadrantids have only been moving in the solar system for the last 500 years or so.
4 תגובות
I have now also checked the original article so now I am sure.
In the commentary it says Big Dipper and the section in brackets does not appear there.
Ran:
It seems to me that you are right in your assumption that there is a small mistake here.
Big Dipper is the big bear and it has seven stars, so it seems that there is both a spelling error and a translation error here.
Hello, I wanted to ask if there is a Hebrew term for the group of seven stars called big deeper? And could it be that there was a mistake and the name is actually big dipper? Thanks