"We discovered that a comet is not really a 'dirty snowball' since dirt is dominant, not ice," said Horst Uwe Keller..."Instead of being spherical like a warm snowball, a comet nucleus is elongated. The physical structure of a comet's interior is defined by its dust content rather than its ice content."
Source -Wiki Some of the NASA links are no longer working for me, they seem to be having more problems.
...comet Borrelly exhibits distinct jets, yet has a hot, dry surface. The assumption that comets contain water and other ices led Dr. Laurence Soderblom of the U.S. Geological Survey to say, "The spectrum suggests that the surface is hot and dry. It is surprising that we saw no traces of water ice." However, he goes on to suggest that the ice is probably hidden below the crust as "either the surface has been dried out by solar heating and maturation or perhaps the very dark soot-like material that covers Borrelly's surface masks any trace of surface ice".
Early on, scientists found surprising evidence that Wild 2 contained some material from the inner solar system that had been heated to more than 1000° C due to its proximity to the Sun....Now, scientists have been surprised again as further study suggests Wild 2 is made mostly of material from the inner solar system
Samples of Comet Wild 2 suggest it is made of rocky material, like an asteroid, rather than the fluffy dust expected of a comet....Wild 2 should still be considered a comet, she adds, because it is throwing off gas and dust [it still has a tail] as ice on its surface evaporates in sunlight. But she says the new findings bolster the view that there is no sharp dividing line between comets and asteroids.
Radiation from the sun pushes dust particles away from the coma. These particles form a tail called the dust tail. At the same time, the solar wind -- that is, the flow of high-speed electrically charged particles from the sun-converts some of the comet's gases into ions (charged particles). These ions also stream away from the coma, forming an ion tail. Because comet tails are pushed by solar radiation and the solar wind, they always point away from the sun.
A team of U.S. and German astrophysicists have made the first ever detection of X-rays coming from a comet. Their discovery of a strong radiation signal -- about 100 times brighter than even the most optimistic predictions -- was made March 27, 1996, during observations of Comet Hyakutake using Germany's orbiting ROSAT satellite....Still another puzzle is the nature of the physical process that generates the X-rays,...[A] possible explanation is that the X-rays are produced from the violent collision between the comet material and the supersonic "wind" of plasma and particles streaming away from the sun.
Using satellite data, an international team of researchers has found that Venus sports a giant, ion-packed tail that stretches almost far enough to tickle the Earth when the two planets are in line with the Sun...."I didn't expect to find it," says team member Marcia Neugebauer of the Jet Propulsion Laboratory in Pasadena, California. "It's a really strong signal, and there's no doubt it's real."
...the team concludes that the satellite [SOHO] may have passed through three separate streams in the ion tail. Alternatively, it may have been a single filament that was "flapping" in the solar wind. "We don't know if we saw the same ray three times, or three different ones," Neugebauer says...Neugebauer suspects the tail is "a lot of little stringy things" like those of some comets, which can have several ion tails.
Samples of Comet Wild 2 suggest it is made of rocky material, like an asteroid, rather than the fluffy dust expected of a comet.
Originally posted by Mogget
Venus is a planet. It has always been a planet, and it always will be a planet. It has never been a comet. Please stop being silly.
Originally posted by daz__
do you remember hale bopp.. within the coma of hale bopp was another object orbiting it..
Planets with a superior orbit to Earth's make that apparent looping or wandering motion but this is not the case for inferior planetary orbits like Venus'.
Originally posted by Anonymous ATS
Retrograde motion is the apparent looping movement of a planet in it's orbit of the Sun.
Source-ESA So what happened to Venus' magnetic field? Did it ever have one and if not then why is the atmosphere 90 times more dense then Earth's? The effects of the solar wind on Venus' atmosphere over 4.5 billion years should have stripped it away by now.
Venus does not possess an intrinsic magnetic field to protect its atmosphere from the solar wind...In particular, the interaction causes Venus’s atmosphere to lose its gases in the form of ionized particles...They are predominantly hydrogen, oxygen and helium ions...ASPERA finally established the composition of the escaping plasma and measured that the escape of hydrogen to oxygen is, indeed, in the same ratio as water.
Venus makes a pentagram
Venus Transit Cycles
Originally posted by mikesingh
Even if Venus was hit by a huge comet, it would well neigh be impossible for the impact to have made it suddenly start rotating in the opposite direction! The colossal impact required for this to have happened would have shattered the planet to bits instead!