Listen to radar echoes from satellites and meteors, live on listener-supported Space Weather Radio. | | |
CHANCE OF FLARES: A cluster of active sunspots has just rotated off the Earthside of the sun. The remaining sunspots facing Earth are quiet, prompting NOAA forecasters to downgrade the chance of geoeffective flares. The odds of an X-class eruption today are no more than 1%. Solar flare alerts: text, voice
SOLAR FLEET PICKS UP COMET ISON: Because NASA's twin STEREO probes are designed to observe the sun, they can see sundiving comets even when the glare becomes intense. Yesterday, Comet ISON joined Earth, Mercury, and Comet Encke in the field of view of STEREO-A's Heliospheric Imager. Click on the image to view ISON's grand entrance:
"The dark 'clouds' of stuff you see coming from the right are density enhancements in the solar wind, and these are what are causing all the ripples you see in comet Encke's tail," explains Karl Battams of NASA's Comet ISON Observing Campaign. "I can pretty much promise you that we're going to see ISON's tail doing that in a couple of day's time, but on a much larger scale!"
Battams points out another exciting development: Comet Encke and Comet ISON are converging for a photogenic close encounter. "No they're not going to hit each other - in reality they are millions of miles apart - but as seen from the STEREO-A spacecraft, they are going to get very close!" he says. "We are probably a couple of days away from seeing two comets almost side-by-side in that camera, with long tails flowing behind them in the solar wind. To say that such an image will be unprecedented is rather an understatement." Stay tuned for that.
Realtime Comet ISON Photo Gallery
ISON, THE DAWN COMET: Comet ISON is plunging toward the sun and brightening as it heads for a perilous close encounter on Nov. 28th. Yesterday morning, with the "final countdown" clock at T-7 days, Juan Carlos Casado photographed the sundiver over the Teide Observatory in the Canary Islands:
"The comet is over the distant island of Gran Canaria," he says, "while in the central cloud we can see the planet Mercury. ISON was at the limit of naked-eye visibility, but it was an easy target for my SLR camera with a small telephoto lens (85 mm focal length) on a static tripod and 6 seconds of exposure."
Because Comet ISON is moving into the rosy glow of dawn, it will soon be impossible for cameras on Earth to track it. Fortunately, NASA's fleet of solar spacecraft are able to follow the comet into the glare. NASA's STEREO-A spacecraft has already picked up Comet ISON. In the days ahead, STEREO-B, SOHO and the Solar Dynamics Observatory will join the hunt, providing continuous views all the way to perihelion (closest approach to the sun) on Nov. 28th.
Realtime Comet ISON Photo Gallery
Ephemerides: Comet ISON, Comet Lovejoy, Comet Encke, Comet LINEAR X
WHY IS COMET ISON GREEN? Taken by hundreds of people around the world, the pictures of Comet ISON we receive every day vary widely in quality, context and camera settings. However, they all seem to have one thing in common: the comet looks green. Why? To answer this question, Italian amateur atronomers Paolo Corelli and Dario Comino used a high-dispersion spectrometer to analyze light from the comet's atmosphere. Here are there results:
The spectrum of Comet ISON is dominated by a green spectral line from diatomic carbon (C2). This substance is common in the atmospheres of comets, and it glows green when illuminated by sunlight in the near-vacuum of space. The spectrum also shows a weaker but still significant blue emission line from C2. Comet ISON's mixture of green and blue light gives it the aqua hue seen in many long-exposure photographs. Finally, the spectrum reveals a contribution from atomic oxygen. This element is familiar to readers of spaceweather.com as a source of green light in auroras.
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
Realtime Comet ISON Photo Gallery
Every night, a network of
NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On Nov. 21, 2013, the network reported 18 fireballs.
(11 sporadics, 5 Leonids, 2 Northern Taurids)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
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 November 22, 2013 there were potentially hazardous asteroids.
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. | | The official U.S. government space weather bureau |
| | The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| | Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| | 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| | Realtime and archival images of the Sun from SOHO. |
| | from the NOAA Space Environment Center |
| | the underlying science of space weather |
