2017 February 21

See Mars and Uranus half-a-degree apart

Stewart Moore

There have been many occasions over the last year to observe the outer planets Uranus and Neptune in close proximity to either brighter planets or the Moon. Unfortunately, as so often happens, many of these occasions have been blighted by bad weather. If you have been one of those unfortunate observers who missed out, there is another opportunity this coming weekend when Uranus and Mars sidle up to each other. In fact on Sunday evening (Feb 27) they are only half-a-degree apart.

 Mars is now well past its best, but still shines at magnitude +1.3 with a disk diameter of 4.6 arc seconds while Uranus only manages magnitude + 5.9 but shows a diameter of 3.4 arc seconds.

 Brilliant Venus at magnitude -4.6 is still dominating the evening sky and at 19:00UT will be around 19 degrees above the western horizon.  So, if first magnitude Mars is difficult to find then Venus acts as a great signpost with Mars and Uranus lying around 11 degrees east of Venus and 24 degrees above the horizon.

 Homing in on Mars and Uranus in a small telescope will show that on February 25 (Saturday evening) at 19:00UT Uranus will be 1 degree east of Mars. On Sunday evening (February 26) Uranus will be only 32 arc minutes south-east of Mars while on the 27th Uranus will be 48 arc minutes south of Mars. If we are very lucky and have a clear sky for these 3 evenings (rather tempting fate, I think!) the perambulations of these 2 planets will make a nice imaging project.

 To add to the show the Moon (new on February 26 at 14:58UT) will be a very thin crescent (6%) on the 28th just 8 degrees above the western horizon.