Comet 17P/Holmes

Latest News...

Date

 Fact
10/31/2007 The Comet (coma) is now the largest thing in our solar system - exceeding even the size of the Sun!
per Chris Peterson: "The visible coma is about 10 arcmin across, and the entire coma as seen in an image is about 20 arcmin across"
10/31/2007 The physical size of the solid nucleus is estimated to be no more than 10 km across (about 6 miles in diameter)
10/31/2007 Current data is not supporting an "impact with an asteroid" scenario to explain this sudden outburst in brightness
   
  What's the deal?
(From Spaceweather.com)		 COMET ERUPTION: Whatever is happening to Comet 17P/Holmes, it's weird. "I've never seen anything like it! It almost looks like a planet," says Eric Allen who recorded this view through a 16-inch telescope at the Observatoire du Cιgep de Trois-Riviθres in Quebec. The comet has no tail, a remarkable golden color, and yesterday it shocked astronomers with a spectacular eruption, brightening almost a million-fold from 17th to 2.5th magnitude in a matter of hours.

"This is unbelievable!" says Iranian astronomer Babak Tafreshi. "I was amazed to find Comet Holmes so easily with the naked-eye in the light-polluted skies of metropolitan Tehran." Click here to see Tafreshi's photo to pinpoint the comet:

The outburst may signify a breakup of the comet's core or perhaps it is merely a fracture exposing fresh ice to vaporize in sunlight, creating the planet-like cloud. No one knows. Comet Holmes is so far away (1.6 AU or 150 million miles from Earth) the details are difficult to see.

"Comet 17P/Holmes is just plain funky," adds Becky Ramotowski who sends this photo from Tijeras, New Mexico. "There's no visible tail, just a bright star-like mystery out there. The comet doesn't get any points for being photogenic. Hopefully that will change."

Amateur astronomers are encouraged to monitor developments. After sunset, point your backyard telescope at the extra "star" in the thigh of Perseus: sky map.

Finder Chart
created with Guide8 software
Comet 17P/Holmes is identified with a purple "17P" near the bottom of the chart.  The blue arched line indicates its change in position at 9:00PM relative to the background stars through Nov 30, 2007

Printer-friendly Chart
created with Guide8 software
Comet 17P/Holmes is identified with a black "17P" near the bottom of the chart.  The red arched line indicates its change in position at 9:00PM relative to the background stars through Nov 30, 2007
   
3D Solar System Graphic • NASA 3D 17P/Holmes
   
Photographs • Image by ACA member, John Crilly
• Image by ACA member, Justin Phillips
• http://publicmissiles.com/franku/Holmes_1minute_exposure.jpg
• http://www.spaceweather.com/swpod2007/24oct07/Babak-Tafreshi1.jpg
• http://www.spaceweather.com/comets/holmes/24oct07/Pierre-Martin1.jpg
• Spaceweather Photo Gallery
   
More Online Information • Chris Peterson's webpage
• Calvin Observatory
• Sky&Telescope Article
• MSNBC story (featuring photo by the ACA'sJohn Crilly!)
• www.spaceweather.com
• http://www.cfa.harvard.edu/iau/Ephemerides/Comets/0017P.html
• http://en.wikipedia.org/wiki/17P/Holmes
• http://www.universetoday.com/2007/10/24/comet-17pholmes-erupts-in-the-sky/
• http://www.arksky.org/smf/index.php?topic=1429.0
  Comet P17/Holmes data (compiled from Guide8 software)

Currently, the comet is on the way out from perihelion (closest point to the Sun in its orbit),
Due to the relative position of the comet and the Earth in their orbits, P17/Holmes is currently
getting closer to us, by about 100,000km/day until Nov 4/5 when it begins receding from us.
(See the chart below)
 
  magnitude (brightness) 16.9 (calculated) - 2.5 actual (!!)    
Period of orbit 6.88 years (2514.1 days)  
Perihelion distance  2.0532180 AU  
Aphelion distance  5.18 AU  

Orbital elements:

    
  Semimajor axis 3.6184134 AU  
Eccentricity 0.4325640  
Inclination of orbit 19.1126000°  
Argument of perihelion 24.2712000°  
Long. ascending node 326.8646000°  
Date of perihelion May 4 2007 12:39:53  
 
Date

 Distance of 17P/Holmes from Earth at 9:30pm

  
Sun Oct 28, 2007 1.62667456 AU = 243,347,051 km = 151,208,849 miles = 13.55 light-minutes Approaching
Mon Oct 29, 2007 1.62518375 AU = 243,124,028 km = 151,070,269 miles = 13.54 light-minutes Approaching
Tue Oct 30, 2007 1.62388343 AU = 242,929,503 km = 150,949,397 miles = 13.53 light-minutes Approaching
Wed Oct 31, 2007 1.62277691 AU = 242,763,970 km = 150,846,539 miles = 13.52 light-minutes Approaching
Thu Nov 1, 2007 1.62186750 AU = 242,627,924 km = 150,762,004 miles = 13.51 light-minutes Approaching
Fri Nov 2, 2007 1.62115846 AU = 242,521,854 km = 150,696,095 miles = 13.50 light-minutes Approaching
Sat Nov 3, 2007 1.62065299 AU = 242,446,236 km = 150,649,109 miles = 13.50 light-minutes Approaching
Sun Nov 4, 2007 1.62035418 AU = 242,401,535 km = 150,621,333 miles = 13.50 light-minutes Approaching
Mon Nov 5, 2007 1.62026504 AU = 242,388,200 km = 150,613,047 miles = 13.50 light-minutes Closest to Earth
Tue Nov 6, 2007 1.62038845 AU = 242,406,662 km = 150,624,518 miles = 13.50 light-minutes Receding
Wed Nov 7, 2007 1.62072717 AU = 242,457,334 km = 150,656,005 miles = 13.50 light-minutes Receding
Thu Nov 8, 2007 1.62128383 AU = 242,540,608 km = 150,707,749 miles = 13.50 light-minutes Receding
Fri Nov 9, 2007 1.62206088 AU = 242,656,854 km = 150,779,981 miles = 13.51 light-minutes Receding
Sat Nov 10, 2007 1.62306066 AU = 242,806,418 km = 150,872,915 miles = 13.52 light-minutes Receding
Sun Nov 11, 2007 1.62428531 AU = 242,989,624 km = 150,986,754 miles = 13.53 light-minutes Receding
Mon Nov 12, 2007 1.62573683 AU = 243,206,768 km = 151,121,681 miles = 13.54 light-minutes Receding
Tue Nov 13, 2007 1.62741703 AU = 243,458,122 km = 151,277,865 miles = 13.56 light-minutes Receding
     

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