October 2013 Sky from the Keeble Observatory
Mars continues to fascinate, and with two active rovers (“Opportunity” and “Curiosity”) operating on the surface, there’s a lot of interesting stuff coming out. Opportunity was launched in July 2003, and has been driving on the Martian surface for 9½ years and almost 24 miles – not bad for a designed 90 day mission!
However, this month, let’s look at two recent findings from Curiosity, which has been on the surface since August 2012 after a launch in November 2011. Last month researchers announced results from an experiment designed to analyze the composition of the Martian atmosphere. Using a tunable laser spectrometer, they have determined that the atmosphere at their current location contains less than 1.3 parts per billion of methane. We have known for some time that the dominant gas in the atmosphere of Mars is carbon dioxide – that hasn’t changed. But there have been remote observations from orbit claiming to find localized concentrations of methane at least 6 times this latest result.
Atmospheric methane can come from geological (areological?) processes like volcanism – but most of the methane in Earth’s atmosphere comes from biological sources (think cow farts, for example!). If the level had been consistent with the earlier orbital estimates of nearly 10 parts per billion, it would have bolstered the notion that some form of life might be extant somewhere on the red planet. That still cannot be ruled out, perhaps as a local phenomenon where earlier indicated, but it seems to rule out anything like active bacteria operating in the vicinity of Opportunity.
The other finding is that the first tested soil samples contained about 2% water! We know that Mars was once a wet place. Earlier probes have found clays, and other minerals known to form in the presence of water. Views from orbit show water formed features like river channels and flood plains. There’s even evidence for the possible shoreline of a large “ocean” in the northern hemisphere. Water would have been essential for any life that we would recognize to develop on Mars – that it’s still there, and far from the polar ice caps, suggests that our search for possible past or present life is not futile. Time will tell.
We’re following the possibility of a bright comet later this fall. We’ll discuss that next month, and perhaps give you a schedule for viewing at the Keeble Observatory at Randolph-Macon College.
Lunar phases for October: New Moon on the 4th, at 8:35 pm; First Quarter on the 11th, at 7:02 pm; Full Moon on the 18th, at 7:38 pm, and Last Quarter on the 26th, at 7:41 pm.
Evening twilight is not going to be friendly for planet watchers this month! Venus and Saturn will be low to the west at sunset, likely lost in horizon clutter and haze. By month’s end Saturn will be lost in the Sun’s glare. Venus will be a bit higher – if you get a clear view to the horizon it will be the first thing to emerge from twilight, but it will set fairly early. Late night and early morning are good times for the planets, however. Predawn twilight finds Jupiter and Mars to the east. Jupiter will be about 60 degrees off the horizon, near Castor and Pollux in Gemini. Mars will be that red “star” below Juiter, near Regulus. Jupiter rises about 1:00 am, and Mars about 3:30. Both will rise earlier as the month goes on, with Jupiter appearing before 11:00 pm by month’s end. Mars’ rising will move to about 2:30 am.
Our midmonth view about three hours after sunset finds the unfamiliar and faint constellation Lacerta at zenith. Your eyes will be drawn west to the familiar Summer Triangle. Deneb in Cygnus is high to the west, about 76 degrees above the horizon. Below Deneb, facing to the west, you’ll find Vega, the brightest of the three at about 55 degrees. A bit further south but at about the same altitude you will find Altair. If you face the southwest horizon and sweep your eyes up to Deneb, you can see why Cygnus (the Swan) is also known as the “Northern Cross.” The Big Dipper is low to the north, just above the horizon. The “house” shape of Cepheus is inverted above the north star, Polaris. The tipped W shape of Cassiopeia is to the northeast. A turn to the east finds the Pleiades rising, anticipating their return to winter skies.
Copyright 2013George Spagna