Dundee Astro - Planetary Notes

Venus will sit 7 degrees directly below Mercury on 22 February but Mercury should still be obvious, around 10 degrees high at 18.00UT. Around this date, just as Venus is setting, Saturn will also be visible some 15 degrees high and back along the ecliptic; another interesting photo-op! Thereafter Mercury sinks closer to the Sun, appearing perhaps 5 degrees high around 18.20UT at the end of February, still keeping company with Venus and Saturn. Mercury moves into the morning sky after 07 March but is very low from the UK and best seen at the very end of the month. The Southern Hemisphere will then have a much better view.

Venus is at the start of its evening apparition so reaches no great elevation in this period but does improve steadily throughout. After playing with Mercury in mid to late February, Venus moves steadily closer to Saturn with the pair very close over 07-08 March. You will start to see magnitude -3.9 Venus from around 18.00UT, some 10 degrees high, but will need binoculars to catch Saturn around 1 degree to the left of Venus; only being really obvious to the naked eye a little before the pair sets. By late March Venus is better placed, some 15 degrees high, due-west, shortly after sunset and showing a 94% illuminated disk, 10 arcseconds in size from pole to pole.

From the UK, Mars rises with the Sun in early February and only slowly stretches further away from it in this period. Even late in March the shallow angle of the ecliptic means that Mars is barely above the horizon at sunrise so save this target for later in the year.

Which brings us to Jupiter. This glorious planet starts February a little past opposition which means initially it is observable for much of the night at an excellent size and brightness. It steadily becomes a mid, and then an early evening object making for comfortable observation hours. It is best seen when transiting, due-south, which happens around 22.26UT in early February, 20.28UT mid-period and 18.32UT at the end of March, then at the start of evening twilight. For much of the UK, south transit is at around 60 degrees of elevation giving the best chance for steady seeing conditions.

Jupiter is moving slowly through Gemini and is very obvious at magnitude -2.6. This magnitude will fall slightly to -2.2 in the period and the apparent size across the equator will shrink from 45.8 to 39 arcseconds; still more than big enough however for excellent detail to be seen. Early on the evening of 12 February you can follow a double shadow-transit event. As darkness falls, the Moon Callisto will have moved off the face of Jupiter but will be very conspicuous near the limb. Europa will be on the disk along with its more obvious shadow, which will be seen near the opposite limb. At 18.44UT Europa is just leaving the disk while its shadow sits at the Central meridian (CM). The shadow of Callisto then enters the disk at 19.03UT and the double shadow transit can be followed until Europa’s shadow leaves the disk at 23.017UT with Callisto’s shadow approaching the CM. Yet another good photo-opp in this period.

Early in February, Saturn will appear shortly after sunset some 25 degrees high in the south-west. The ring system stretches 38 arcseconds wide with rings tilted 2.2 degrees towards us; the southern side more open as seen from Earth. This opens further to 3.6 degrees in the period but Saturn itself sinks ever lower towards the Sun. By mid-period Saturn isn’t really visible until just 10 degrees above the western horizon, so seek it out earlier in February if possible. On 01 March Venus is very obvious low in the west after sunset with Saturn 7.5 degrees higher and back along the ecliptic, and on 07 and 08 March, Venus sits next to Saturn which may help you find it in early twilight; the pair setting together a little after 19.00UT. Saturn is lost to solar conjunction on 25 March.

If you wish to find Neptune then you might just catch it early in February as it sits close to Saturn. For the first couple of weeks, Neptune sits almost directly above Saturn with the pair just a degree apart. After mid-February Neptune is increasingly lost to twilight, this conjunction marking the end of its apparition.

Uranus is better placed. In early February it transits, around 55 degrees high, at 18.50UT, in early twilight. The Pleiades cluster acts as a good marker with magnitude +5.7 Uranus sitting 5 degrees below and just a little west of that cluster. Uranus will not then set until well after midnight and can still be seen more than 30 degrees high in the west around 22.50UT. By early March, south-transit is just before sunset but Uranus will be more than 40 degrees high in the south-west around 20.00UT, still sitting 5 degrees below the Pleiades. Thereafter it becomes harder to catch and late in March is effectively lost to twilight.