Comets

Hale-Bopp from Indian Cove

Title	Hale-Bopp from Indian Cove
Explanation	Good cameras [ http://www.chimacum.wednet.edu/highschool/jeff/Photo/camera/camera3.html ] were able to obtain impressive photographs of Comet Hale-Bopp [ http://galileo.ivv.nasa.gov/comet/ ] when at its brightest earlier this year. In the above photograph [ http://galileo.ivv.nasa.gov/comet/pach9.html ] taken April 5th, Comet Hale-Bopp was imaged from the Indian Cove Campground in the Joshua Tree National Forest [ http://www.nps.gov/jotr/ ] in California, USA. A flashlight was used to momentarily illuminate foreground rocks in this 30 second exposure. Comet Hale-Bopp is still visible [ http://www.eso.org/outreach/info-events/hale-bopp/comet-hale-bopp-summary-aug01-97-rw.html ] to the unaided eye in Earth's Southern Hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap951222.html ], with observers there reporting it to be about 4th magnitude [ http://liftoff.msfc.nasa.gov/academy/universe/MAG.HTML ]. The comet is now passing nearly in front of the star Sirius [ http://antwrp.gsfc.nasa.gov/apod/ap960902.html ], and shows only a slight dust tail [ http://antwrp.gsfc.nasa.gov/apod/ap970403.html ].

Comet Hale-Bopp Over Val Par …

Title	Comet Hale-Bopp Over Val Parola Pass
Explanation	Comet Hale-Bopp became much brighter than any surrounding stars. It was seen even over bright city lights. Out away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomite mountains surrounding Cortina d'Ampezzo, Italy. Comet Hale-Bopp's blue ion tail was created when fast moving particles from the solar wind struck expelled ions from the comet's nucleus. The white dust tail is composed of larger particles of dust and ice expelled by the nucleus that orbit behind the comet. Observations showed that Comet Hale-Bopp's nucleus spins about once every 12 hours.

Comet Hale-Bopp

This image of Comet Hale-Bop …

3/20/97

Date	3/20/97
Description	This image of Comet Hale-Bopp was taken by Jim Young of JPL's Table Mountain Observatory, approximately 30 miles east of Los Angeles in Wrightwood, CA, on March 12, 1997, at 4:21 a.m. PST, and was taken with a 135mm telephoto lens mounted on a 35mm camera at an aperture of f/4 and an exposure time of eight minutes. The bright head of the comet, called the coma, is pointed toward the Sun. The coma is composed of dust and gas, masking the solid nucleus of the comet made up of rock, dust and ice. The bluish tail seen heading away from the comet is the comet's ion tail, visible because of sunlight reflecting off of singly ionized carbon monoxide particles that fluoresce into visible wavelengths. The white tail pointing away from the comet is the dust tail, visible from sunlight reflected off of dust particles ejected from the comet over millions of miles of space.

Hale-Bopp's Fickle Ion Tail

Title	Hale-Bopp's Fickle Ion Tail
Explanation	What's happening to Comet Hale-Bopp's blue ion tail? The comet's ion tail [ http://antwrp.gsfc.nasa.gov/apod/ap960502.html ] is fluctuating more rapidly as it passes a region of changing solar wind [ http://antwrp.gsfc.nasa.gov/apod/ap970217.html ]. As the comet passes from north to south, it crosses the plane of the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap970226.html ]'s equator, where the solar magnetic field [ http://www.hao.ucar.edu/public/workshop/smi/sum_low_atmos.html ] changes direction. Ions from the solar wind [ http://lepmp.gsfc.nasa.gov/Education/wsolwind.html ], which cause Comet Hale-Bopp [ http://galileo.ivv.nasa.gov/comet/ ]'s ion tail, act unpredictably here. Therefore, Comet Hale-Bopp's ion tale may show unusual structure or even a disconnection [ http://www-istp.gsfc.nasa.gov/istp/halebopp/disconnect/ ] - where the tail appears to break off and then reestablish itself later. The above picture [ http://www.sunrise.it/associazioni/aac/comete/95o10497.htm ], taken April 30th, indeed shows unusual structure in the blue ion tail.

A Hale-Bopp Holiday

Title	A Hale-Bopp Holiday
Explanation	Seen from the Pik Terskol Observatory [ http://www.mpae.gwdg.de/mpae_projects/gbo/terskol.html ] in the northern Caucasus mountains, comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap971215.html ] and the bright stars of the constellation Perseus [ http://www.astro.wisc.edu/~dolan/constellations/ constellations/Perseus.html ] hang above the snowy, moon-lit landscape [ http://antwrp.gsfc.nasa.gov/apod/ap970327.html ]. Although it reminds Northern Hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap971221.html ] dwellers of an idyllic Winter [ http://antwrp.gsfc.nasa.gov/apod/ap951225.html ] scene, this picture was actually recorded [ http://www.astro.uni-bonn.de/~skohle/comets/hbxmas.html ] in the spring - on April 13th of this year. Seasons Greetings [ http://antwrp.gsfc.nasa.gov/apod/ap961225.html ] and Best Wishes from APOD [ http://antwrp.gsfc.nasa.gov/apod/ap960616.html ]!

Comet Hale-Bopp Over Indian …

Title	Comet Hale-Bopp Over Indian Cove
Explanation	Comet Hale-Bopp, the Great Comet of 1997 [ http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search?great+comet+1997 ], was quite a sight. No comets [ http://www.nineplanets.org/comets.html ] of comparable brightness have graced the skies of Earth [ http://antwrp.gsfc.nasa.gov/apod/ap010204.html ] since then. During this next month, however, even besides the fleeting Comet Bradfield [ http://antwrp.gsfc.nasa.gov/apod/ap040419.html ], "two" comets have a slight chance of rivaling Hale-Bopp [ http://www2.jpl.nasa.gov/comet/ ] and a good chance of putting on a memorable [ http://antwrp.gsfc.nasa.gov/htmltest/gifcity/comet.html ] sky show. Unfortunately, most of the show will be confined to sky gazers in Earth's southern hemisphere [ http://antwrp.gsfc.nasa.gov/apod/ap021222.html ]. Both comets are already visible [ http://encke.jpl.nasa.gov/RecentObs.html#02T7 ] to the unaided eye from there. The first, Comet C/2002 T7 (LINEAR) [ http://cometography.com/lcomets/2002t7.html ], should be at its best before dawn during the first weeks of May from the south. The second, Comet C/2001 Q4 (NEAT) [ http://cometography.com/lcomets/2001q4.html ], should be visible in early May from all over the Earth. Both comets [ http://www.space.com/spacewatch/comet_double_040319.html ] appear to be approaching [ http://skyandtelescope.com/observing/objects/comets/article_1037_1.asp ] the inner Solar System [ http://www.nineplanets.org/overview.html ] for the first time and so it is very hard to predict [ http://www.exploratorium.edu/exploring/space/kohoutek.html ] how bright each will become. In the above photograph [ http://www2.jpl.nasa.gov/comet/pach17.html ] taken 1997 April 6, Comet Hale-Bopp was imaged from the Indian Cove Campground in the Joshua Tree National Forest [ http://www.nps.gov/jotr/ ] in California [ http://www.state.ca.us/ ], USA [ http://www.cia.gov/cia/publications/factbook/geos/us.html ]. A flashlight [ http://www.geocities.com/~stuarts1031/flashlight.html ] was used to momentarily illuminate foreground rocks during this six minute exposure.

Hale-Bopp and the North Amer …

Title	Hale-Bopp and the North American Nebula
Explanation	Comet Hale-Bopp [ http://galileo.ivv.nasa.gov/comet/ ]'s recent encounter with the inner Solar System [ http://antwrp.gsfc.nasa.gov/apod/ap961214.html ] allowed many breath-taking pictures. Above, Comet Hale-Bopp [ http://encke.jpl.nasa.gov/hale_bopp_info.html ] was photographed on March 8th in the constellation of Cygnus [ http://astro.gmu.edu/constellation/CYG.html ]. Visible on the right in red is the North American Nebula [ http://antwrp.gsfc.nasa.gov/apod/ap960606.html ], a bright emission nebula [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#emis_neb ] observable from a dark location with binoculars. The North American Nebula [ http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1989A%26A%2E%2E%2E222%2E%2E%2E82S&db_key=AST&nosetcookie=1 ] is about 1500 light years away, much farther than the comet, which was about 8 light minutes away. Several bright blue stars from the open cluster [ http://antwrp.gsfc.nasa.gov/apod/ap970128.html ] M39 are visible just above the comet's blue ion tail [ http://antwrp.gsfc.nasa.gov/apod/ap960502.html ].

Two Tails of Comet West

Title	Two Tails of Comet West
Explanation	Here Comet West is seen showing two enormous tails that wrap around the sky. The ion tale of a comet [ http://antwrp.gsfc.nasa.gov/apod/lib/glossary.html#comet ] usually appears more blue and always points away from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap950813.html ]. The dust tail trailing the comet's nucleus is the most prominent. Comet West was a visually spectacular comet [ http://seds.lpl.arizona.edu/billa/tnp/comets.html ], reaching its most picturesque in March of 1976. A comet [ http://www.c3.lanl.gov/~cjhamil/SolarSystem/comet.html ] this bright occurs only about once a decade. Comets are really just large dirty snowballs that shed material when they reach the inner solar-system. Many astronomers are hopeful that Comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap950820.html ] will look as spectacular as this in the spring of 1997. Tomorrow's picture: Gamma Ray Bursts from the Unknown

General Description	STS-83 Shuttle Mission Imagery

Sirius: The Brightest Star i …

Title	Sirius: The Brightest Star in the Night
Explanation	Sirius is the brightest star [ http://www.astro.wisc.edu/~dolan/constellations/extra/brightest.html ] in the night sky. Sirius [ http://www.louisville.edu/~aoclar01/ancient/astronomy/Sirius.htm ] is visible on the far left of the above photograph, to the left of the constellation [ http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html ] of Orion [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Orion.html ] and Comet Hale-Bopp [ http://antwrp.gsfc.nasa.gov/apod/ap970429.html ]. Intrinsically, Sirius [ http://www.physics.purdue.edu/astr263l/forum/Sirius.html ] is over 20 times brighter than our Sun [ http://antwrp.gsfc.nasa.gov/apod/sun.html ] and over twice as massive. As Sirius [ http://www.wshs.fcps.k12.va.us/academic/science/bjewell/ocean/zittel/final/stars.htm ] is 8.7 light years distant, it is not the closest star system - the Alpha Centauri [ http://antwrp.gsfc.nasa.gov/apod/ap960526.html ] system holds this distinction. Sirius [ http://www.star.le.ac.uk/edu/ask/stars_faq.html#9 ] is called the Dog Star because of its prominence in the constellation of Canis Majoris [ http://www.astro.wisc.edu/~dolan/constellations/constellations/Canis_Major.html ] (Big Dog). In 1862, Sirius [ http://www.astro.wisc.edu/~dolan/constellations/hr/2491.html ] was discovered to be a binary star system with a companion star, Sirius B [ http://www.dcn.davis.ca.us/~btcarrol/skeptic/dogon.html ], 10,000 times dimmer than the bright primary, Sirius A. Sirius B was the first white dwarf star discovered, a type of star first understood by Subrahmanyan Chandrasekhar [ http://antwrp.gsfc.nasa.gov/apod/ap950901.html ] in 1930. While studying Sirius [ http://antwrp.gsfc.nasa.gov/apod/ap960902.html ] in 1718, Edmond Halley [ http://antwrp.gsfc.nasa.gov/apod/ap960706.html ] discovered that stars move with respect to each other. There is conflicting evidence that Sirius appeared more red [ http://www.louisville.edu/~aoclar01/ancient/astronomy/Sirius.htm ] only 2000 years ago.

The Ion Tail of Comet Hyakut …

Title	The Ion Tail of Comet Hyakutake
Explanation	This picture of Comet Hyakutake [ http://www.eso.org/educnpubrelns/phot-23-96.html ] was taken on March 14, 1996. Structure in the ion tale of Comet Hyakutake [ http://www.astro.washington.edu/astro422/comets.html ] is now clearly visible. An ion tale forms as a comet nears the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap950813.html ]. Sunlight causes gas and dust to boil off the comet's solid nucleus. Charged gas - called ions - are then accelerated away from the Sun [ http://antwrp.gsfc.nasa.gov/apod/ap951004.html ] by the solar wind [ http://www-spof.gsfc.nasa.gov/Education/wsolwind.html ] - fast moving particles streaming out from the Sun's corona [ http://antwrp.gsfc.nasa.gov/apod/ap951024.html ]. The ion tale will appear blue and glows by fluorescence [ http://charlie.ab.umd.edu/jf/info.html ]. As Comet Hyakutake [ http://cfa-www.harvard.edu/cfa/ps/info1996B2.html ] gets closer to the Sun during the next month, a dust tail is expected to be visible as well. Dust [ http://antwrp.gsfc.nasa.gov/apod/ap960125.html ] tails shine by light reflected from the Sun. Comet tails [ http://antwrp.gsfc.nasa.gov/apod/ap950826.html ] point away from the Sun, even as a comet moves away from the Sun. For observers in the Northern Hemisphere, Comet Hyakutake should appear tonight [ http://encke.jpl.nasa.gov/C1996B2/C1996B2_guide.html ] in the eastern part of the constellation of Virgo and should be about magnitude 2.5. The comet will look the most impressive in the darkest skies - in a city you are likely to see only a fuzzy blob!

These images show Comet Hall …

Description

These images show Comet Halley as it was photographed on various dates in 1910 from Diamond Head, Hawaii, by Ferdinand Ellerman. The points or short streaks are background stars. During its current apparition, the comet is the subject of the International Halley Watch (IHW), a worldwide observation effort by professional and amateur astronomers. The Jet Propulsion Laboratory is the Western Hemisphere lead center for the IHW. (Courtesy of Mount Wilson and Las Campanas Observatories of the Carnegie Institution of Washington.) (Note to editors: "Halley" rhymes with "valley.")

Media Group: Comets