You are viewing the page for Oct. 29, 2007
  Select another date:
<<back forward>> -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
Current conditions
Solar wind
speed: 577.4 km/sec
density: 4.1 protons/cm3
explanation | more data
Updated: Today at 2245 UT
X-ray Solar Flares
6-hr max: A0
2245 UT Oct29
24-hr: A0
1220 UT Oct29
explanation | more data
Updated: Today at: 2245 UT
Daily Sun: 29 Oct 07
The sun is blank--no sunspots. Credit: SOHO/MDI
Sunspot number: 0
What is the sunspot number?
Updated 28 Oct 2007
Far side of the Sun:
This holographic image reveals no large sunspots on the far side of the sun. Yesterday's apparent detection of a large spot was noise--not a real sunspot. . Image credit: SOHO/MDI
Planetary K-index
Now: Kp= 5 mild
24-hr max: Kp= 5
explanation | more data
Current Auroral Oval:

Switch to: Europe, USA, New Zealand, Antarctica
Updated: 2007 Oct 29 2142 UT
What is the auroral oval?
Interplanetary Mag. Field
Btotal: 6.9 nT
Bz: 2.4 nT south
explanation | more data
Updated: Today at 2246 UT
Coronal Holes:
There are no large coronal holes on the sun today. Credit: Hinode X-ray Telescope
NOAA Forecasts
Updated at: 2007 Oct 29 2203 UTC
0-24 hr
24-48 hr
01 %
01 %
01 %
01 %
Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2007 Oct 29 2203 UTC
0-24 hr
24-48 hr
15 %
10 %
10 %
05 %
01 %
01 %
High latitudes
0-24 hr
24-48 hr
15 %
10 %
10 %
05 %
01 %
01 %

What's up in Space
October 29, 2007
Where's Saturn? Is that a UFO--or the ISS? What's the name of that star? Get the answers from mySKY--a fun new astronomy helper from Meade.

BEWARE THE GOBLIN: "Just in time for Halloween -
a Goblin Comet!" says Terry Pundiak who took this spooky picture of Comet 17P/Holmes through his 16-inch telescope in Easton, Pennsylvania. Contrary to appearances, the core of the comet has not split in two. The two eyes are an illusion caused by background stars shining through the comet's gaseous envelope: gallery.

EXPLODING COMET: Exploding Comet 17P/Holmes is now larger than Jupiter. Astronomer Eric Allen of Quebec's Observatoire du Cégep de Trois-Rivières combined images he captured on three consecutive nights (Oct. 25, 26 and 27) and placed them beside a picture of Jupiter scaled to the same distance as the comet:

The diaphanous and curiously spherical cloud surrounding the comet's core is now large enough to physically swallow the King of Planets!

And that's just for starters. The growing comet subtends an angle (4 arcminutes) as large as the Moon's Sea of Tranquillity. Last night in Higham Ferrers, England, Dave Eagle photographed "the Moon and Comet Holmes with the same setup to show how big this strange comet is."

Although the comet is not as bright as Jupiter or a lunar mare, it is visible to the unaided eye. Look north after sunset for a magnitude +2.5 fuzzball in the constellation Perseus: sky map.

What would make a comet explode in this fashion? Actually, a better question is, what would make a comet explode twice in this fashion? This is the second time Comet 17P/Holmes has erupted. The first was in 1892, an outburst that led to the comet's discovery by British astronomer Edwin Holmes.

The answer may be sinkholes. There is growing evidence that some comets and asteroids may have a porous internal structure akin to, say, swiss cheese or a honycomb. Suppose one of the chambers of the honycomb suddenly collapsed, exposing many square kilometers of fresh cometary ice to sunlight for the first time. A flurry of sublimation would ensue with mega-jets of dusty gas emerging from the sinkhole to create a cloud around the comet much as we see now. Twice = two sinkholes, one in 1892 and one in 2007. (Many readers have asked if the explosion might be a result of a cosmic collision. Perhaps an asteroid hit the comet. While possible, such an event is unlikely to happen once and it is unlikely2 to have happened twice.)

Because no one can see the comet's nucleus--it is small, far away and hidden inside a Jupiter-sized debris cloud--this "explanation" is no more than conjecture. The true events at the core of Comet Holmes remain unknown. Grab your telescope and savor the mystery!

Comet 17P/Holmes Photo Gallery
[New: Interactive World Map of Comet Photos]
[sky map] [ephemeris] [3D orbit] [Night Sky Cameras]

Near-Earth Asteroids
Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.
On October 29, 2007 there were 894 potentially hazardous asteroids.
Oct.-Nov. 2007 Earth-asteroid encounters:
Miss Distance
2007 TL16
Oct. 5
1.6 LD
27 m
2007 TC14
Oct. 18
11.7 LD
180 m
2340 Hathor
Oct. 22
23.3 LD
620 m
2005 GL
Nov. 8
8.0 LD
280 m
1989 UR
Nov. 24
27.6 LD
880 m
Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.
Essential Links
NOAA Space Environment Center
  The official U.S. government bureau for real-time monitoring of solar and geophysical events, research in solar-terrestrial physics, and forecasting solar and geophysical disturbances.
Atmospheric Optics
  The first place to look for information about sundogs, pillars, rainbows and related phenomena.
Solar and Heliospheric Observatory
  Realtime and archival images of the Sun from SOHO.
Daily Sunspot Summaries
  From the NOAA Space Environment Center
Current Solar Images
  from the National Solar Data Analysis Center
  more links...
©2007, -- This site is penned daily by Dr. Tony Phillips.
©2019 All rights reserved.