Cassini has found hints of activity coming from the Saturn moon Dione.
The spacecraft’s magnetometer has detected a faint particle stream coming from the moon, and images showed evidence for a possible liquid or slushy layer under its rock-hard ice crust. Other Cassini images have also revealed ancient, inactive fractures at Dione similar to those seen at Enceladus that currently spray water ice and organic particles.
Not only can the very fast rotation of neutron stars sometimes speed up suddenly, scientists have now discovered that their rotation can suddenly slow as well.
The neutron star, 1E 2259+586, is located about 10,000 light-years away toward the constellation Cassiopeia. It is one of about two dozen neutron stars called magnetars, which have very powerful magnetic fields and occasionally produce high-energy explosions or pulses. Observations of X-ray pulses from 1E 2259+586 from July 2011 through mid-April 2012 indicated the magnetar’s rotation was gradually slowing from once every seven seconds, or about eight revolutions per minute. On April 28, 2012, data showed the spin rate had decreased abruptly, by 2.2 millionths of a second, and the magnetar was spinning down at a faster rate.
Astronomers had a theory which explained the sudden increase in a neutron star’s rotation. They don’t have one yet for why this star slowed.
Dark matter, WIMPS, and NASA’s Alpha Magnetic Spectrometer
This very nicely written article describing the scientific goals of AMS is even better in that it emphasizes strongly the uncertainties of the data and the theories behind it.
Scientists have released the first topo map of Titan.
Whereas Earth’s tallest mountain towers nearly 9 kilometers above sea level, Titan’s topographic variations are mild: Its highest point is just half a kilometer above the mean and its lowest just 1.7 kilometers below.
Overall the detail here is not very great. None of the instruments on Cassini can see anything smaller than a half kilometer, about 1,500 feet, so the data doesn’t really show us the rough details. Moreover, the best data is spotty, as it has been accumulated by about a hundred Cassini fly-bys, rather than systematically by an orbiting spacecraft.
The impact of a 100 pound meteorite on the Moon in March produced the brightest flash ever recorded.
Anyone looking at the Moon at the moment of impact could have seen the explosion–no telescope required. For about one second, the impact site was glowing like a 4th magnitude star.
Ron Suggs, an analyst at the Marshall Space Flight Center, was the first to notice the impact in a digital video recorded by one of the monitoring program’s 14-inch telescopes. “It jumped right out at me, it was so bright,” he recalls.
The 40 kg meteoroid measuring 0.3 to 0.4 meters wide hit the Moon traveling 56,000 mph. The resulting explosion1 packed as much punch as 5 tons of TNT.
It will be really interesting to see the Lunar Reconnaissance Orbiter images of the impact site, which can’t be taken until the spacecraft passes over the site and can photograph it.
The Kepler mission has lost its second gyroscope, ending the ability of the telescope to aim precisely. More details here.
The telescope’s primary mission, to stare continuously at one section of sky, looking for exoplanet transits, is over, though it might still be re-purposed for other astronomical research.
Last Saturday the space telescope Swift detected the most powerful gamma ray burst ever detected.
You can see the raw reports of the detection, followed up immediately by a host of other ground-based and space-based observations at this website. Click on the circulars for GRB130427A, starting with circular 14448. When this happened last Saturday I was out camping. When I got home there were dozens of circulars to look at. Based on the data here, this gamma-ray burst was relatively close for a grb, approximately 3.6 billion light years away.
The lingering echo of Comet Shoemaker-Levy in the atmosphere of Jupiter.
The Herschel observations, together with heat maps provided by NASA’s Infrared Telescope Facility on Mauna Kea, showed the researchers that the Jovian stratosphere was 20° to 30°F (10° to 15°C) warmer than it would be if completely dry. One question is whether the stratospheric warming results from the gentle, continuous infall of interplanetary dust particles, which would be warmed by sunlight as they linger high up. Cavalié and his colleagues believe IDPs create some of the infrared emission but cannot explain it all. Further, a continuously supplied source would migrate to lower depths, yet most of the emission is too high up, at pressures less than 2 millibars. And while the amount of water is roughly constant across the southern hemisphere, the emission gradually weakens northward until it’s less than half as strong. It’s not simply that Jupiter’s bottom half is hotter — there’s just more water down there. As the researchers note, “At least 95% of the observed water comes from the SL9 comet and subsequent (photo)-chemistry in Jupiter’s stratosphere according to our models, as of today.
Taken together, they conclude, these observations offer “clear evidence that a recent comet … is the principal source of water in Jupiter. What we observe today is a remnant of the oxygen delivery by the comet at 44°S in July 1994.”
Astronomers have discovered a previously unknown neighbor galaxy to the Milky Way.
A rose by any other name: In a NASA contest, a nine-year-old has named asteroid 1999 RQ36 after the Egyptian god Bennu.
1999 RQ36, or Bennu, is an important asteroid for two reasons. First, NASA is sending an unmanned sample return mission to it in 2016. Second, some calculations suggest the asteroid has a 1 in a 1000 chance of hitting the Earth in 2182.
In other naming news, the private space company Uwingu has launched its “Adopt-a-Planet” campaign.
This open-ended campaign gives anyone in the public—worldwide—the opportunity to adopt exoplanets in astronomical databases via Uwingu’s web site at www.uwingu.com. Proceeds from the naming and voting will continue to help fuel new Uwingu grants to fund space exploration, research, and education.
As noted earlier, they are ignoring the IAU’s stuffy insistence that only the IAU can name things in space.
The Herschel Space Telescope has closed its eye on the universe.
After four years of operation, the telescope’s supply of helium coolant has run out, leaving the infrared telescope blind to the sky.
Cassini snaps an amazing image of Saturn’s north pole vortex.
