Rosetta and Siding Spring--comets in the news

I opened Jupiter-Venus conjunction by musing about how to handle my backlog of space and astronomy stories.

I have all kinds of space news from the past two weeks of Overnight News Digest: Science Saturday, enough for a post every day this week.  In fact, I might just do that.

Follow over the jump for the next installment, comets in the news.

First, JPL presents The Rosetta Mission Asks: What is a Comet?

The Rosetta Mission Asks: What is a Comet? Scientists attempt to answer these questions and more as the Rosetta Mission’s Orbiter arrives and escorts comet 67/p Churyumov Gerasimenko into our inner solar system.

Space.com has more in Rosetta Spacecraft Takes Temperature of Comet 67P By Elizabeth Howell, Space.com Contributor, on August 14, 2014 05:30pm ET.

As the European-built Rosetta spacecraft neared its close encounter with a comet last week, it turned up a cosmic surprise: the comet is warmer than scientists were expecting.

The Rosetta probe took the temperature of Comet 67P/Churyumov-Gerasimenko as well as high-resolution photos of the comet ahead of its Aug. 6 arrival at the icy celestial wanderer. From a distance of 145 miles (234 kilometers) away — less than the distance between New York City and Baltimore — Rosetta revealed a pockmarked nucleus that appears to have some higher sections than others. The comet itself has been compared to a rubber ducky due to its shape.

Temperatures of the comet taken in mid-July by the Rosetta's visible, infrared and thermal imaging spectrometer — nicknamed VIRTIS for short — show that the average surface temperature is minus 94 degrees Fahrenheit (minus 70 degrees Celsius).

Rosetta's target is not the only comet in the news.  There will be another encounter in October, as Science at NASA reports in ScienceCasts: Colliding Atmospheres - Mars vs Comet Siding Spring.

Comet Siding Spring is about to fly historically close to Mars. The encounter could spark Martian auroras, a meteor shower, and other unpredictable effects. Whatever happens, NASA's fleet of Mars satellites will have a ringside seat.

Stay tuned for more installments of space news.