Here's the latest from Karl Battams: "As I expected, the comet "pulled an ISON". I won't even describe it as a comet any longer. It's a rubble pile." (SunGrazerComets).
Friday, August 28, 2015
We see comets because they evaporate ices and other compounds from their surface. This cools the comet, but makes it disappear. The water ice that comes off the comet quickly turns into Hydrogen and Oxygen atoms. SDO sees comet tails when the oxygen atoms hit the electrons in the corona. We can use the tails to explore the Sun's magnetic field and corona.
Most Kruetz sungrazing comets are too small to make it to perihelion (Comet Lovejoy in December 2012 was the only exception). We can only watch as this comet goes behind the LASCO occulter disks and hope it continues to evaporate and be seen in SDO/AIA images.
Thursday, August 27, 2015
We will try to post images as fast as we can tomorrow afternoon. Perihelion is at 1947 UTC (3:47 pm ET).
Tuesday, August 25, 2015
This picture shows the edge of the Earth against the Sun in AIA 193. You can see the edge of the Earth is rough, where the absorption of the Earth's atmosphere dims but does not block the light. This is different from the lunar transits, such as the one coming up on September 13, where the Moon's edge is very crisp. That transit occurs near the end of that day's eclipse and coincides with a solar eclipse in the far southern parts of the Earth.
Eclipse season is a result of our geosynchronous orbit. We don't like missing the Sun for up to 72 minutes each day. But the constant contact with SDO allows the high speed data downlink we use to bring the Sun to everyone.
Wednesday, August 12, 2015
The next eclipse season starting August 25, 2015, giving us more chances to see the Earth's limb against the Sun. Eclipse season ends September 17.
The next lunar transit on September 13 will have two firsts. The eclipse by the Earth will happen just before the transit and finish while the Moon is still crossing the Sun. At the same time a partial solar eclipse will be visible in the South between Antarctica and Africa. This will be the first time an SDO lunar transit could be seen as a solar eclipse on Earth. The movie of the combined eclipse and transit looks like a race between two spacecraft.