SJAA Ephemeris March 2011 | SJAA Home | Contents | Previous | Next

The Last Month in Astronomy


10-FEB-2011 • 3 Shuttles • Shuttle flights 133, 134 and 135 are upcoming. Discovery flies STS-133 taking spare parts to the ISS in late February. STS-134 (Endeavour) will be commanded by Mark Kelly and it will deliver the Alpha Magnetic Spectrometer. Atlantis may launch as early as June 28. It is the last shuttle launch and it will deliver the Raffaello module. Wait a minute? Haven’t we said “last shuttle launch” before? Well, STS-135 might not be the last launch either. At least one speculation has it that Endeavour will be kept in launch ready condition and it will be used once a year by a non-government company until 2017 when NASA will once again have a method for putting astronauts into orbit.

)08-FEB-2011 •Stardust at 12• Not many spacecraft get to celebrate their 12th anniversary at all. But fewer still celebrate by firing up the rockets. That’s what Stardust did on its way to a rendezvous with Tempel 1. Does the comet name sound familiar? Deep Impact flew by Tempel 1 in 2005. Scientists are hoping to see changes that have occurred in the intervening years.

08-FEB-2011 •Europa Adaptive Optics• Franck Marchis and other astronomers using the high resolution infrared camera at the Keck Observatory wanted to make use of the adaptive optics - the technology that allows a telescope to handle atmospheric aberrations by making up to 2,000 changes per minute. But that technology needs a guide star usually created with a laser. But Marchis et. al. wanted to look into the clouds of Jupiter and the laser-created guide star was not bright enough compared to Jupiter. The solution? Use Europa as the guide star. The result is high resolution infrared images of Jupiter that exceed what Hubble can do.

03-FEB-2011 •Mars Changing• The Mars Reconnaissance Orbit has taken notice of the changes in Northern Mars. The dunes were once thought to be fairly static but changes, both sudden and gradual, can be seen. Some changes are the result of sand avalanches. Why in the North? It might be that winds are stronger near the poles. Over a 2 Mars-year period, 40% of the sites monitored showed major changes.

02-FEB-2011 •Exoplanets Abound• In what might already be the biggest astronomical news story of 2011, NASA’s Kepler mission announced that more than 1200 planet candidates have been found. Note that these candidates are only from the first 4 months worth of data. They are called “candidates” because their transit of their star has been seen just twice. If the next transit occurs as expected the candidates will be confirmed. It is expected that at least 80% of the candidates will be confirmed. At least 5 of these planets appear to be Earth-sized planets located in the goldilocks zone (not too hot, not too cold). Furthermore, there is now clear evidence that Jupiter and larger planets are rare. Most of the new candidates are around Neptune-size and the discovery-bias is still pointing to larger planets. Most of the planet candidates are around Sun-like stars, stars with surface temperatures near 6000K. Since this is based on 4 months of data, the longest orbits take about 120 days. At this rate, it will take until late 2012 before Earth-sized planets in an Earth-sized orbit will be discovered. At the same time, NASA announced the discovery of a 6 planet system around a star now called Kepler-11. The planet furthest from Kepler-11 is much closer than Venus is to the Sun. This is interesting because it wasn’t known that so many planets could be found in such a compact system. See the diagrams on page 3.

20-JAN-2011 •Black holes<>Dark matter• One theory has it that a black hole at the center of a galaxy is related to a dark matter halo. Well, maybe not. Scientists at the Max Planck Institute in Germany have shown the black hole is related to the bulge in the galactic center. They found that galaxies without a central bulge even with a massive dark matter halo can have low mass black holes at best. Ralf Bender said “It is hard to conceive how the low-density, widely distributed non-baryonic dark matter could influence the growth of a black hole in a very tiny volume deep inside a galaxy.”

12-JAN-2011 •(Not so) Standard Candle• Cepheids, the variable stars that are used as a standard candle to estimate distances to deep sky objects, may not be so standard after all. The problem is that Cepheids lose mass through stellar winds. Cepheids were used to determine that galaxies are not “spiral nebulae” within our own galaxy. They were also used by Hubble to determine that the universe is expanding. The drop in mass was determined using the Spitzer Space Telescope studying the “original” Cepheid, Delta Cephei. The result doesn’t mean that past discoveries are void but it does mean the future Cepheid measurements could be more accurate, i.e. reduce the error bar.


Previous | Contents | Next