October and November 2014
Planetary Section Report; October/November 2014
For this reporting period only the lonely ice-giants, Uranus and Neptune, were well placed in the evening skies however Jupiter became accessible for pre-dawn observation and the section’s ‘early-birds’ managed to capture interesting detail that will bear watching as this giant planet’s visibility improves and moves to less antisocial hours. There were also glimpses of other solar-system objects so I will begin by covering the visual observations made by Mike Feist during the reporting period. He managed to view faint and distant Mars, low in the south-south-west on the evening of the 9th of November but could report no visible detail, similarly he saw Mercury in the pre-dawn skies of the 28th of October and the 6th of November, this being either side of mercury’s greatest western elongation from the Sun on November 1st, with a distinct phase visible telescopically and the planet appearing “bright to the unaided eye”.
Mike also made a number of observations of the Asteroid Hebe, sending me visual reports of its movements against the background stars from the 22nd to the 25th of October. At just 8th magnitude Mike needed his 102mm telescope to pick out this 118-mile-wide rock moving slowly east to west across the stars of Eridanus, below the feet of Taurus; at some 163 million Km distance, Mike did extremely well to identify and track this object over several evenings. Mike finished the reporting period by glimpsing Venus as she returned to the evening sky at the end of November. With the planet less than 10 degrees from the Sun he was able to safely do this by letting the Sun set behind a local hill and was able to see Venus himself just before the planet set.
Moving on to the better placed planets on view: Neptune attracted little attention as its tiny apparent size makes detailed views very difficult; large amateur instruments can show variations in atmospheric shading but that is all I would expect to see and even then only under the steadiest of skies. However Graham Taylor used the Bradford Robotic Telescope (BRT), a remotely operated 14” telescope on Tenerife, to capture a wide field view around the planet on the 8th of November. The image shows Neptune as a tiny pale blue disc, lost in a sea of background stars, and is remarkably sharp given that it is a single exposure.
Graham used the same telescope to capture Uranus on the 6th of October and, as is more usual from a single image, there is little detail on view; however an over-exposed image taken on the same night allows us to see four faint moons around it; in this case, Oberon, Umbriel, Ariel and Titania. Mike is considering attempting to stack a number of BRT images as well as trying out a new planetary video camera on his own telescope. Uranus has been the cause of great interest in both the amateur and professional communities recently. As previously reported, unexpected brightening and increased activity in the northern hemisphere along with very large and bright atmospheric storms have been imaged in the infra-red (IR) by a professional team using the Keck telescope. Some amateurs have also succeeded in imaging them with their own telescopes using standard monochrome planetary cameras and filters that pass light from the deep-red end of the spectrum and into the near infra-red. To capture the storms requires steady skies for this tiny target but brightening of the northern hemisphere at high latitudes is easier to capture.
Richard Hill sent in an image taken on the first of October using a one-shot-colour (OSC) camera that shows a general brightening of the northern hemisphere but cannot show storm detail due to the IR-cut filter he employed; the blue-green colour of the planet is well displayed however. Then Michael Andrews sent in two images taken on the 4th of October. Like Graham Taylor, Michael over-exposed one video stream to reveal four moons, and then took a correctly exposed video using a 685Nm IR-pass filter on his C11 telescope and an ASI monochrome camera; the result is very interesting. While not showing a distinctly brighter North-Pole region it does show a large bright patch at higher latitudes. This could just be an artefact from image processing but the patch is asymmetric and this is suggestive that he may have caught a blurred version of a large storm feature. I tried to match the general position of Michael’s ‘storm’ with that of the known feature and failed but very recently have learned that the biggest storm seen by Keck, at around 2 micron frequency (IR), is not the same feature being captured by amateurs; that is a slightly smaller storm, more visible at shorter IR wavelengths. Most amateur cameras have no capability beyond around 1 micron so are just not seeing the biggest feature; I will try to match Mike’s image with the new data when this becomes available.
Michael also sent in a final image on the 9th of November which captured a clear disc with some lightening towards the North Pole but was otherwise featureless. Uranus presents a challenging imaging project but Images and observations will continue to be of importance and I hope that section members with larger telescopes will give this target a try and pass their results to me in the next reporting period. I must now move on to Jupiter.
The largest planet in our solar-system was well placed for observation but only if you were prepared to be up in the very early hours before dawn. For this reason there were relatively few observations submitted but some major points were noted. Michael Andrews sent in a series of images throughout the reporting period and his contributions, along with others from Steve Norrie and Graham Taylor, form the backbone of this Jupiter report. The main points of interest noted are as follows:-
Firstly that the faint Equatorial Band (EB), a narrow dark belt at the centre of the normally pale Equatorial Zone (EZ) and whose existence was only suspected at the end of the last reporting period, was actually formed from trailing extensions of extremely large festoons spreading down from the North Equatorial Belt (NEB). These festoons seem unusually active and, early in the period, stretched so far as to form a visible EB. By the 4th of November this continuous band had faded away ‘though many festoons were still large by the end of the reporting period.
Secondly the ‘Little Red Spot’, more correctly known as Oval BA, had successfully negotiated its way just past and to the South of the Great Red Spot (GRS) without any apparent problems. Between the two there is a broad, pale, South Tropical Zone (STropZ). Over most of the visible circumference this zone is unmarred by obvious darker belts though there are hints of one trailing Oval BA and prograde of the GRS there are also hints of small black spots that may presage a renewed breakout of a South Temperate Belt (STB).
Finally the GRS itself looks visibly shrunken in size with an obvious empty and pale area separating it from the South Equatorial Belt. While still by far the largest storm feature on the planet it is no longer massively larger than Oval BA and I would welcome all observations of Jupiter so as to continue monitoring the progress of this feature. I will finish the section report by mentioning that the Juno Mission, a probe currently in transit to Jupiter will be able, on arrival in 2016, to make highly detailed observations of narrow strips of the planet on each orbit. The exact features viewed will depend on the final orbit chosen for the probe and to help in deciding on this a substantial Pro-Am collaboration is being set up. Amateurs can provide the kind of continuous coverage of the planet unavailable to professionals and can point out important changes and unexpected events. I would like SPA members to help with this project and will publish any details as to how when they become available to me.
Looking ahead: December into January next year.
Mercury moved into superior conjunction with the Sun on the 8th of December making it effectively unobservable for most of the rest of the month but from early January 2015 it improves and becomes visible as an evening object shortly after sunset. It reaches its point of greatest elongation to the east of the Sun, as seen from Earth, on the 14th of January when it will be trailing 19 degrees behind as the Sun sets. Unfortunately, due to Mercury’s current position to the south of the ecliptic it will only rise, at best, some 8 degrees above the south-western horizon, as seen from mid-UK latitudes, reaching this high-point on the 18th of January some 30 minutes after sunset; Its visibility improves the further south you have your observing site. As the month progresses Mercury then moves closer to the Sun, reaching inferior conjunction between the Earth and the Sun on January 30th.
Venus is only slightly better placed than Mercury but improves throughout the period. It is visible from the UK on the last few days of December very low on the south-western horizon shortly after sunset. Like Mercury it is far south of the celestial equator and so better seen from more southerly latitudes but its greater distance from the Sun means we can view it at more favourable angles with the horizon. At the Start of January Venus is very close to Mercury but much more obvious. Mercury will shine at a magnitude of -0.6 while Venus will be a striking beacon shining at -3.6 and while Mercury fades and declines after mid-month, Venus continues to rise with each sunset, itself setting more than 2 hours after the Sun by the end of January.
Mars is not well placed throughout this period. While it doesn’t actually set until mid-evening it is only seen low over the southern to south-western horizon shining as a first magnitude object; its visible face is just some 4 seconds of arc across and shrinking further as time passes so detailed observation is not possible. Mars does not become a prominent object again until 2016.
Undoubtedly Jupiter is the most magnificent object on display over the next couple of months and onwards into early 2015. It rises before midnight as an obvious beacon in the eastern to south-eastern sky brightening from magnitude -2.2 to -2.4 during December and in January it is observable from mid-evening and all through the rest of the night, transiting due-south at 0100ut at the end of the month some 52 degrees above the horizon from mid-UK latitudes. Jupiter’s orbit around the Sun takes a little under 12 Earth years to complete and twice during each of its rotations it reaches a point where its orbiting moons are seen exactly edge-on from our viewpoint on Earth; we are currently passing through one of these periods which means there will be a sequence of observable mutual events where these moons eclipse each other or where the shadows of one moon pass across the face of another.
As an example on the 14th of December the moon Io will pass directly behind Ganymede at 01.10ut with Ganymede grazing just under Callisto at 03.35ut. I will shortly publish a list of these line-of-site events as a news story on the website giving details of observable events through December and into January next year.
I must also mention a rare triple-shadow transit event on Jupiter. On the 24th of January from 06.28ut until 06.54ut three shadows, cast by Jupiters own moons Io, Europa and Callisto, will be visible on the face of Jupiter at the same time. The last time this happened was June 3rd 2014 and prior to that 12th October 2013 which suggests these events come at least once a year but in fact they are much rarer, appearing in a cluster of two or three such events, and the next time three shadows will be visible on the face of Jupiter will be 20th March 2032; don't miss this one if you can possibly do so! More details about this event will appear as a news story in early January with details of just what will be on view.
Saturn in December and January is an early morning object in the constellation of libra rising in the south-east some 3 hours before the Sun and shining at around magnitude +0.6, but it will be seen very low-down from UK latitudes. It improves somewhat through January, rising earlier each night but it is still below 15 degrees of elevation in the south by full light.
Uranus has its best mid-evening visibility of the year during December, transiting due south in full darkness at around 1820ut towards the end of the month at some 40 degrees of elevation. At a magnitude of +5.8 it is only just on the edge of naked-eye visibility but is an easy binocular object and will show a distinct blue-green planetary disc when viewed through a telescope with a mid or high-powered eyepiece. Planetary imagers equipped with a monochrome camera and deep-red or infra-red filters might like to try and capture the large storm features still visible on this planet and mentioned both in the section reports and elsewhere as a news story. By the end of January Uranus is still visible as an evening object being some 40 degrees up in the south as darkness falls and setting at 22.55ut by month’s end.
Neptune in December is past transit by full evening darkness and can be seen at around 20 degrees of elevation in the south-west around 18.00ut. It is a binocular or telescopic object only at magnitude +7.9. It declines further to the west with each sunset through January, setting at around 19.00ut by month’s end. On the 19th of January it will be seen in close conjunction with Mars with the two planets just 1/3rd of a degree apart.
I look forward to seeing all your images and observations as we move forward and into the New-Year.