By Duncan Lunan
The Moon will be Full on October 13th, New on October 28th. It will pass through the Hyades Open Cluster in Taurus on October 17th, and through the Praesepe cluster in Cancer on the morning of the 22nd.
The planet Mercury is in the evening sky in October, at greatest elongation from the Sun on the 20th, but very low and setting about 5.30 p.m. (BST, ending on October 27th).
Venus appears low in the evening sky in late October, setting only minutes after Mercury, with the Moon very near on the 29th. On October 30th the thin crescent Moon is between Venus and Jupiter.
Mars in Virgo rises about 6 a.m. in late October. The Moon appears near Mars on October 26th.
Methane Gas on Mars
In 2012, astronomers using telescopes on Hawaii announced the detection of methane gas in the atmosphere of Mars, during autumn in the northern hemisphere of Mars. (Seasons there are twice as long as ours.) This would be a very important discovery because methane isn’t chemically stable in the atmosphere of Mars – it gets decomposed quickly by ultraviolet rays from the Sun, so for it to last long enough to be detected, something would have to be making it or releasing it. Mars has no animal life, or surface vegetation to decompose, so it would have to come from some form of life underground (probably bacteria), or from volcanic activity. Although Mars has lots of volcanoes there’s no visible surface activity, but there’s lots of frozen water in the crust, so if there are hot spots underground, they could provide habitats for life even if it doesn’t generate the methane.
Confirmation by space probes on Mars or in orbit round it would be good, and sure enough, Europe’s Mars Express detected methane in the atmosphere for a time in July 2013, in the same general area of the planet, and around the time of the Martian spring equinox. The Curiosity rover, on the surface in Gale crater, then detected outbursts of methane in 2014, before the Martian summer solstice. Further analysis of the gas detected by Curiosity looks more like biological methane than volcanic (due to the isotope ratios), but of course on Mars conditions could be different.
Europe’s Trace Gas Orbiter went into orbit round Mars last year, specifically to look for methane among other gases, and when I was on BBC Radio Scotland’s Newsdrive in March this year, it was because the spring equinox had come and gone without finding any. I said then that if it did appear, it would probably be in September – and indeed it now has!
Two very important new details are that the gas is being emitted within Gale crater itself, where the Curiosity rover has found lots of evidence for surface water in the ancient past. Also, when the gas is being emitted in early summer, it goes on by day and night. During the day the methane gets scattered by the winds, which is probably why there was too little for TGO to detect at first; but during the night the winds drop and there are higher concentrations near the ground at sunrise, and TGO has now detected these.
You wouldn’t expect volcanic activity to be seasonal, but it’s still possible that methane’s being released from deposits in the soil, though that looks less and less likely – they’d have to be too deep for the ground to warm up like that. Unless, of course, the deposits are being renewed during the winter by life that’s deep enough in the soil to escape the cold… !
With the US Insight probe there now, trying to measure whatever heat is coming from the Martian interior, and with both the USA and Europe sending still more sophisticated equipment on rovers next year, this story just keeps getting more interesting.
Jupiter in Ophiucus sets about 8.30 p.m. in October, near the Moon on the 3rd and 31st.
Saturn in Sagittarius sets about 10.30 p.m. in October. The Moon is near Saturn on October 5th.
Uranus in Aries is at opposition on October 28th, at its nearest to us for the year and due south at midnight.
Neptune in Aquarius sets at about 4 a.m. in October.
The Orionid meteor shower from Halley’s Comet peaks on the night of 21/22nd October, with some interference from moonlight. Taurid meteors can be seen throughout October and November, along with occasional meteors from the Leonid shower which peaks on November 17/18th.
The Astronomers of the Future Club
At the Astronomers of the Future Club meeting on Thursday October 31st the guest speaker will be Dr. Alan Cayless of the Open University in Scotland, on ‘Astronomy in a Volcanic Landscape’, describing his latest exploits on Tenerife, and the new online course which will allow anyone remote use of the OU telescopes there. The meeting will be from 19:15 to 21:00 hrs at the RSAS Barassie Works Club, 4 Shore Road, Troon, KA10 6AG. For more details, contact Alan Martin on 07947 331632.
Duncan Lunan’s new book “From the Moon to the Stars”, a collection of space travel stories old and new relating to the Moon and Project Apollo, is now available from the publishers at https://othersidebooks.wordpress.com, as well as on Amazon or through booksellers; details of that and his other books are on Duncan’s website, www.duncanlunan.com.