The Solar and Heliospheric Observatory (SOHO) was launched in 1995 and is positioned in a stable orbit at a point between the Earth and the Sun, where the gravitational forces of the two bodies exactly cancel each other. Consequently, the SOHO is fixed in space between Earth and Sun, and thus is at a prime position to monitor the Sun:).
As comets orbit around the Sun and once in a while crash into it, the SOHO takes their pictures. Scores of volunteers pore through the videos from the craft, and often are the first to spot new comets. Toni Scarmato, a high school teacher from Italy, discovered SOHO's 999th and 1000th comet recently, when two comets appeared in the same SOHO image:):).
The twin comets (Courtesy: SOHO)
SOHO has also been used to discover three other well-populated comet groups: the Meyer, with at least 55 members; Marsden, with at least 21 members; and Kracht, with 24 members. These groups are named after the astronomers who suggested the comets are related, because they have similar orbits.
Almost all SOHO's comets are discovered using images from its Large Angle and Spectrometric Coronagraph (LASCO) instrument. LASCO is used to observe the faint, multimillion-degree outer atmosphere of the sun, called the corona. A disk in the instrument is used to make an artificial eclipse, blocking direct light from the sun so the much fainter corona can be seen. Sun grazing comets are discovered when they enter LASCO's field of view as they pass close by the star.
A large animation of the comets can be found here.
As comets orbit around the Sun and once in a while crash into it, the SOHO takes their pictures. Scores of volunteers pore through the videos from the craft, and often are the first to spot new comets. Toni Scarmato, a high school teacher from Italy, discovered SOHO's 999th and 1000th comet recently, when two comets appeared in the same SOHO image:):).
The twin comets (Courtesy: SOHO)
SOHO has also been used to discover three other well-populated comet groups: the Meyer, with at least 55 members; Marsden, with at least 21 members; and Kracht, with 24 members. These groups are named after the astronomers who suggested the comets are related, because they have similar orbits.
Almost all SOHO's comets are discovered using images from its Large Angle and Spectrometric Coronagraph (LASCO) instrument. LASCO is used to observe the faint, multimillion-degree outer atmosphere of the sun, called the corona. A disk in the instrument is used to make an artificial eclipse, blocking direct light from the sun so the much fainter corona can be seen. Sun grazing comets are discovered when they enter LASCO's field of view as they pass close by the star.
A large animation of the comets can be found here.
1000th Comet!
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10 Comments:
Given the sun is very, very, very, very, very, very .. very hot, is it fair to say that the comets simply vapourize?
Kepler's third law of motion defines orbital periodicity ... and requires that an object closer to the sun move faster.
The period for a body to orbit the Sun increases rapidly with the radius of its orbit. By way of example, Mercury takes only 88 days to orbit the Sun, but Pluto requires 248 years to do so.
So it seems likely that SOHO is in an orbit closer to the sun, but it is not "fixed" between the earth and the sun. Sometimes it must be on the opposite side of the sun and earth's gravity is irrelevant.
/e
The Keplerian law is for a idealized planet/other object (perfectly spherical, uniform density) orbiting another idealized point star/other object. When three bodies are involved, it is a classic three-body problem, and you have those five fixed-points in space.
my apologies. great site. discovered yesterday. don't think i'll be able to resist visiting daily.
thanks for publishing this incredible array of neat stuff.
/e
but how is it possible for some comets to shoot back out? what would that depend on? just curious.
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