January 2021 What’s Up!

Week of 25th January

  • Astronomical twilight ends at 18:42 UT at the beginning of the week and at 18:51 UT by the end of the week
  • On Wednesday, Mercury (mag -0.1) reaches its highest point in the evening sky at 13° altitude. It will be visible in the southwest after sunset (16:48 UT) until it sets at 18:30 UT. Take care if using binoculars
  • The Moon is Full on Thursday
  • The Sun currently has three visible active regions (AR 2797, AR 2798 & AR 2799). The sunspot number is 34
  • The ISS makes visible evening passes this week as follows:

    Monday: 18:32, WSW to E, max 82° & 20:09, W, max 12°
    Tuesday: 17:45, WSW to E, max 68° & 19:22, W, max 38°
    Wednesday: 18:34, W to E, max 84° & 20:11, W, max 12°
    Thursday: 17:47, W to E, max 88° & 19:24, W, max 40°
    Friday: 18:36, W to E, max 89° & 20:13, W, max 12°
    Saturday: 17:49, W to E, max 85° & 19:26, W to WSW, max 38°
    Sunday: 18:38, W to SE, max 63° & 20:16, W, max 11°

Week of 18th January

  • Astronomical twilight ends at 18:32 UT at the beginning of the week and at 18:40 UT by the end of the week
  • Mars and Uranus appear close together this week, easily fitting in to the field of view of a pair of 10×50 binoculars. On Wednesday they will be at their closest, with a separation of just 1° 37 minutes and on Thursday they will be joined by the waxing Gibbous Moon, just a few degrees away.
  • Mercury reaches greatest elongation east on Sunday and will be visible sinking from about 10° above the southwestern horizon for the hour after sunset. Take care if using binoculars
  • The Moon is First Quarter on Wednesday
  • The Sun has one small active region (AR 2796) currently visible. The sunspot number is 15
  • The ISS makes visible evening passes this week as follows:

    Tuesday: 18:29, S to SSE, max 14°
    Wednesday: 19:16, SW to SSW, max 21°
    Thursday: 18:29, SSW to E, max 29°
    Friday: 17:41, SSW to SE, max 21° & 19:17, WSW to WSW, max 33°
    Saturday: 18:29, SW to ESE, max 52° & 20:06, W to W, max 12°
    Sunday: 17:42, SW to E, max 39° & 19:18, W to W, max 39°

Week of 11th January

  • Astronomical twilight ends at 18:23 UT at the beginning of the week and at 18:31 UT by the end of the week
  • On Thursday, look to the southwest just after sunset to see the very young, 3% waxing crescent Moon almost in line with Mercury (mag. -0.9), Jupiter (-1.9) and Saturn (0.6). You will need to be quick as Saturn sets at 17:08 UT, just 42 minutes after sunset. Take care when looking towards the setting Sun, especially if using binoculars
  • The Moon is New on Wednesday
  • The Sun has no visible active regions now. The spotless stretch is 7 days
  • There are no visible ISS evening passes this week

Week of 4th January

  • Astronomical twilight ends at 18:15 UT at the beginning of the week and at 18:22 UT by the end of the week
  • Following the Great Conjunction, Mercury approaches the two Gas Giants in the evening sky on Saturday. The three planets will form a triangle covering only about 3° in the southwestern sky. Look at around 16:20 UT, about half an hour after sunset, to see Mercury (mag -0.9) only about 5° above the horizon, with Saturn (0.6) 1.5° away at about 7° altitude and Jupiter (-1.9) another 2° away about 8° above the horizon
  • The Moon is Last Quarter on Wednesday
  • The Sun currently has two active regions, AR 2794 & AR 2795, both very close to the off going limb – the sunspot number is 22
  • There are no visible ISS evening passes this week
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