what is hallet's comet?
442132
In 1705 Edmond Halley predicted, using Newton's newly formulated laws of motion, that the comet seen in 1531, 1607, and 1682 would return in 1758 (which was, alas, after his death). The comet did indeed return as predicted and was later named in his honor. \n\nThe average period of Halley's orbit is 76 years  but you cannot calculate the dates of its reappearances by simply subtracting multiples of 76 years from 1986. The gravitational pull of the major planets alters the orbital period from revolution to revolution. Nongravitational effects (such as the reaction from gasses boiled off during its passage near the Sun) also play an important, but smaller, role in altering the orbit. Between the years 239 BC and 1986 AD the orbital period has varied from 76.0 years (in 1986) to 79.3 years (in 451 and 1066). The closest perihelion passage to the time of Jesus are 11 BC and 66 AD; neither event took place in Jesus' lifetime. Its most famous appearance was in 1066 when it was seen at the Battle of Hastings, an event commemorated in the Bayeux Tapestry.
323618
That would be comet 73P/Schwassmann-Wachmann starting about the end of April and until about June 15th.  Uncertain how bright (as with most comets) will become, but it will be relatively close to earth at 11 million miles.  It should be visible as it travels through the constellation of Hercules and glide past the star Vega on its journey.  On May 11, it  will be in the constellation Cynus the Swan (aka the Northern Cross).  It will continue through Pegasus and Pisces, and dim from view in Cetus in mid June.
1138155
Soon! From June 10-21, we should see the June Lyrids meteor shower in the northern hempisphere\n\nhttp://comets.amsmeteors.org/meteors/showers/june_lyrids.html\n\nA site with great info on comets and meteor showers is http://comets.amsmeteors.org/index.html (BTW, you should see the Shoemaker 1 comet tonight)\n\nAlso, for stars in general, I highly reccommend \nhttp://skyandtelescope.com/observing/\n\nIt has a really great interactive map function... also, they offer a customised star chart, v cool!\nhttp://skyandtelescope.com/observing/skychart/article_1220_1.asp\n\nHope that helps!
655485
There will be no tsunamis, firestorms or mass extinctions to spoil your Memorial Day weekend. \n\nAlthough the Internet is rife with speculation that a fragment of Comet 73P/Schwassmann-Wachmann 3 will strike the Earth on May 25, neither the main comet nor any of its more than 40 fragments pose a danger to Earth. \n\n"We are very well acquainted with the trajectory of Comet 73P Schwassmann-Wachmann 3," said Donald Yeomans, manager of NASA's Near-Earth Object Program Office. "There is absolutely no danger to people on the ground or the inhabitants of the International Space Station, as the main body of the object and any pieces from the breakup will pass many millions of miles beyond the Earth."\n\nImage above: Hubble's Advanced Camera for Surveys took images of the disintegration of Comet 73P/Schwassmann-Wachmann 3's fragment B. Click to EnlargeCredit: NASA, ESA, H. Weaver (APL/JHU), M. Mutchler and Z. Levay (STScI)\nMovie: Zoom to Fragment B close-up: + 544 Kb QuickTime | + Windows Media \n\nHowever, you can see the comet falling apart right before our eyes, thanks to NASA's Hubble Space Telescope. \n\nRecent Hubble images have uncovered many more fragments than have been reported by ground-based observers. These observations provide an unprecedented opportunity to study the demise of a comet nucleus. \n\nNone of the comet's fragments will come closer than 5.5 million miles to Earth during its closest approaches May 12 - 28. That's more than 20 times the distance from the Earth to the moon.\n\nThe main fragment, designated fragment C, will pass closest to Earth on May 12 at a distance of approximately 7.3 million miles. It will be visible to small telescopes during the morning hours in the constellation Vulpecula. NASA's Spitzer Space Telescope will observe the comet in May. \n\nAstronomers have been observing the comet for more than 75 years. The trajectory of this comet has been monitored and refined over time, and its path around the sun is well understood. Amateur and professional astronomers around the world have been tracking its spectacular disintegration for years. \n\nThe comet is currently comprised of a chain of fragments, named alphabetically, stretching across several degrees on the sky. (The sun and moon each have an apparent diameter of about 1/2 of a degree.) Ground-based observers have noted dramatic brightening events associated with some of the fragments (as seen in the image below) indicating that they are continuing to break-up and that some may disappear altogether.\n\n Image above: Ground based view of fragments B and G, R, and N on April 8, 2006. Credit: M. Jäger and G. Rhemann \n\nHubble caught two of the fragments, B and G, shortly after large outbursts in activity. Hubble also photographed fragment C , which at the time was less active. The resulting images reveal that a hierarchical destruction process is taking place, in which fragments are continuing to break into smaller chunks. Several dozen "mini-fragments" are found trailing behind each main fragment, probably associated with the ejection of house-sized chunks of surface material that can only be detected in these very sensitive and high- resolution Hubble images.\n\nSequential Hubble images of the B fragment, taken a few days apart, suggest that the chunks are pushed down the tail by outgassing from the icy, sunward-facing surfaces of the chunks, much like space-walking astronauts are propelled by their jetpacks. The smaller chunks have the lowest mass, and so are accelerated away from the parent nucleus faster than the larger chunks. Some of the chunks seem to dissipate completely over the course of several days.\n\nDeep-freeze relics of the early solar system, cometary nuclei are porous and fragile mixes of dust and ices. They can be broken apart by gravitational tidal forces when they pass near large bodies. For example, Comet Shoemaker-Levy 9 was torn to pieces when it skirted ne
634196
I love the vomit comet statement.  I understand that Ron Howard used this when making Apollo 13.
1080538
A ball of ice in many cases or a rock that has ice and what not breaking off as dust. That is why we can see the trails behind a comet.
533962
The link below has great overview info and statistics (including density) for all the planets, asteroids, comets, etc. \n\nCheck it out!
134289
There are several things. Right now comet Pojmanski is visible in the morning sky. Also Mercury is visble. In a month the Lyrid metershower will peak. Events like these are constantly posted on www.spaceweather.com
1120403
well let me tell you look up the shoemakers. they are a couple who are homebred amatures and sure they are a bit more into it then most but they have at least 3 comet names under their belt. they actually pulled a bunch of money together in their life and made thier own observatory (or bought a old used one) even though we have many satelites like hubble that patrol our skies but they only mechanically watch about 20% of total viewable sky surrounding earth. the shoemakers are still making discoveries and sightings and they get to put their name on whatever they spot as new not yet seen. this requires dedication and hard work not to mention a dedicated memorization of every fart of gas visible to the aided eye because they need to know that when they see that new bubble, fart, blinking light, or whatever that they have a potential lead to something new and not something that has been there billions of years!
935624
The evolution of a comet. We did that last year to show how a comet becomes an asteroid. We used dry ice, dirt, dark corn syrup. It was fun. And we had live demonstration and lots of pictures. This link has a comet recipe: http://www.noao.edu/education/crecipe.html\n\nHere's another site that you can look for ideas: http://www.spartechsoftware.com/reeko/MoreExperimentsSortCategory.htm
37735
Stars are like our Sun. Not comets at all. Comets are dirty, big snowballs that have no light at all. The twinkling comes from heat radiating from earth which makes the light spectrum shift in different colours. Symbols that represent something doesn't often look like the original. Take the symbol for a heart for example. But it's easy! :) Try to draw a immensly huge boiling, burning piece of gas that throws tons of particles out from it in lightning speed and see if anyone understands what you drew. Now try to make it into a character that you can type on a keyboard :)
526778
Shoemaker-Levy 9. Hubble telescope took more pictures. Due to the gravity of Jupiter, the comet broke into several pieces and in July 1994 collided with Jupiter. The fragments speed was about 60 Km/s.
527999
ha ha ha, i herd about it too, but i herad also that that comet will pass near the earth and it won't hit it. I heard also that in som cpuple bilions of years our galaxy will crash will another galaxy blah blah blah ... i think all these will happne at some time, but i don't know when
787239
Maybe you are referring to the "Hayashi Track" that protostars move along prior to reaching the main sequence. The question is a little vague, so  I am unsure. Here is the wiki link.  \nhttp://en.wikipedia.org/wiki/Hayashi_track
480373
stars, planets, comets, meteors
1044389
Comets, as several people have pointed out, are large bodies of rock and ice that orbit the sun. When they come close enough to the sun, energy from the sun causes some of the ices to vaporize, causing a visible coma (cloud around the nucleus) and tail, consisting of gas and dust.\n\nA meteor is the streak made in the upper atmosphere by a bit of high-velocity space debris. The bits of debris themselves are called meteoroids. The ones that produce predictable meteor showers are clouds of dust shed by comets. Other meteoroids are  pieces of primordial matter that never accreted into planets, or chunks of matter broken off of larger bodies by impacts with asteroids. \n\nA meteoroid that makes its way to the surface of Earth is called a meteorite. They can be stony, metallic, or both. Some meteorites have been identified as coming from Mars and the Moon.
420776
a comet is a ball of rock and ice that orbits the sun on a large elliptical orbit.  THey usually are not in the normal orbital plane of the planets so we only see them once in a while. So if the planets go around and around like on a plate, comets go on an angle like a plate on a 75 degree angle.  And instead of the sun being close to the center of the plate, with comets, the sun is much closer to the edge of the plate.\n\nSome planets take far longer than 76 years to orbit (pluto, neptune, etc...) so their orbits are even larger.  But they are more regular, comet's orbits are more stretched out so they get closer to the sun.