DOOMED COMET: The sun is about to swallow a comet. The doomed sungrazer appeared earlier today in images from the Solar and Heliospheric Observatory (SOHO):
“This is one of the brightest Kreutz sungrazers we’ve seen over the past 21 yrs,” says Karl Battams of the Naval Research Lab in Washington DC. “Awesome! ”
Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. Kreutz fragments pass by the sun and disintegrate almost every day. Most, measuring less than a few meters across, are too small to see, but occasionally a bigger fragment like this one attracts attention.
The comet is vaporizing furiously and is not expected to survive much longer. Monitor the SOHO realtime images page for developments. Updates are also available on Karl Battam’s excellent Twitter feed.
SUMMERTIME AURORAS: It’s not often that a flash of lightning and distant peal of thunder makes you look up and see … green. Yet that’s what happened on the night of Aug.2-3 when auroras backlit a summer thundercloud over Center, Wisconsin. Extreme weather photographer Jeremy Friebel captured the moment:
“I took the picture from cornfield around 1 am,” says Friebel.
The display occurred scant hours after a solar wind stream hit Earth’s magnetic field, igniting a G1-class geomagnetic storm. At high latitudes, a rare apparition of summertime auroras lit the skies of the northern hemisphere. Thunder heralded green lights over Canada, Europe, and a handful of northern-tier US States.
The odds of more auroras are waning as Earth exits the solar wind stream. NOAA forecasters say there is a 40% chance minor geomagnetic storms on August 4th.Aurora alerts: text or voice
WHAT HAPPENED TO SDO? NASA’s Solar Dynamics Observatory (SDO) is in a geosynchronous orbit high above Earth with a 24/7 view of the sun. Occasionally, however, the Moon gets in the way. On Aug. 2nd, SDO observed a beautiful eclipse as the dark lunar disk moved in front of the sun:
SDO has recorded many lunar transits since the observatory was launched in 2010. This one was different from the others in one important way:
“The spacecraft did not go back into Science mode at the end of the transit,” writes Dean Pesnell of NASA/Goddard on the SDO blog. “SDO FOT members are looking into the issue.”
Since the transit no new data have appeared on SDO public websites. Did the shadow of the Moon cause a dip in voltage for the solar-powered spacecraft? We don’t know. Stay tuned for updates from the SDO team at NASA.