May 2021 – What’s Up!

Week of 31st May

  • Astronomical twilight does not end until 00:55 BST on 21st July
  • This week’s challenge is to hunt down the array of Globular Clusters above the arc of the Milky Way. These include M3 (in Bootes), M13 (the Great Hercules Cluster) and M92 (in Hercules), M5 (in Serpens) and M10 and M14 (in Ophiuchus). Binoculars or a small telescope will suffice to spot these magnificent balls of stars
  • The Moon is Last Quarter on Wednesday
  • The Sun currently has two active regions, AR 2824 (off going) and AR 2827 (a new on coming region). The sunspot number is 26
  • There are no visible evening ISS passes this week

Week of 24th May

  • Astronomical twilight does not end until 00:55 BST on 21st July
  • Noctilucent cloud season starts around now, so keep an eye out near the northern horizon around 90 minutes after sunset to try and spot these beautiful, high level night shining, opalescent clouds
  • There is a total lunar eclipse on Wednesday. Unfortunately, it is not visible from the UK, but only visible from Oceania, the Americas and Eastern and Southeast Asia
  • The Moon is Full on Wednesday – the Flower Moon. As the Moon will be very close to perigee, this will make it a ‘supermoon’. It will be the largest and brightest full Moon of 2021
  • The Sun currently has one active region, AR 2824. The sunspot number is 19
  • The ISS makes the following visible evening passes this week:
    Monday: 21:58, W to E, max 89° and 23:35, W to S, max 49°
    Tuesday: 22:48, W to SE, max 53°
    Wednesday: 22:00, W to ESE, max 68° and 23:37, W to SSW, max 21°
    Thursday: 22:49, W to SSE, max 29°
    Friday: 22:02, W to SE, max 39°
    Saturday: 22:52, WSW to SSW, max 15°
    Sunday: 22:04, W to SSE, max 21°

Week of 17th May

  • Astronomical twilight ends at 00:02 BST at the beginning of the week, but by the end of the week, here at a latitude of 51° North, the Sun will no longer sink more than 18° below the horizon, meaning that astronomical twilight does not end. We will not experience astronomical darkness again until the 21st July
  • Mercury reaches greatest elongation east this week on Monday, placing it at its greatest separation from the Sun. Look for the planet low to the west-northwestern horizon just after sunset
  • The waxing Moon provides a good target this week, where plenty of surface detail can be observed, especially along the Terminator – the line separating night and day on the Moon
  • The Moon is First Quarter on Wednesday
  • The Sun currently has two active regions, AR 2822 and AR 2823. The sunspot number is 24
  • The ISS makes the following visible evening passes this week:
    Monday: 22:40, WSW to E, max 64°
    Tuesday: 21:56, SW to E, max 49° and 23:29, W to E, max 85°
    Wednesday: 22:41, W to E, max 89°
    Thursday: 21:54, WSW to E, max 78° and 23:31, W to E, max 89°
    Friday: 22:43, W to E, max 84°
    Saturday: 21:56, W to E, max 85° and 23:33, W to ESE, max 68°
    Sunday: 22:45, W to ESE, max 82°

Week of 10th May

  • Astronomical twilight ends at 23:34 BST at the beginning of the week and at 00:02 BST by the end of the week
  • On Thursday, the very thin, 1.8 days old, waxing Crescent Moon will be in conjunction with Mercury (mag +0.1), separated by about 2.5°. Look at around 14° altitude above the west-northwest horizon at about 21:00 BST, after sunset. You will also find Venus (-3.9) lower down, just above the horizon
  • On Sunday, Mercury will reach its highest point in the sky for this apparition, sitting at an altitude of 16° at 21:00 BST
  • The Moon is New on Tuesday
  • The Sun currently has one active region, AR 2822. The sunspot number is 17
  • The ISS makes the following visible evening passes this week:
    Friday: 21:51, SSE to ESE, max 13° and 23:25, SW to E, max 49°
    Saturday: 22:38, SW to E, max 36°
    Sunday: 21:51, SSW to E, max 26° and 23:27, WSW to E, max 78°

Week of 3rd May

  • Astronomical twilight ends at 23:07 BST at the beginning of the week and at 23:30 BST by the end of the week
  • The Eta-Aquariid meteor shower peaks on Thursday. Best prospects for observing inceased meteor numbers are in the early pre-dawn hours, when the Zenithal Hourly Rate is expected to be around 30-40. This meteor shower is created by debris deposited by comet 1P/Halley
  • Mercury appears low to the northwestern horizon shortly after sunset this week. On Tuesday, look at an altitude of about 9° and azimuth of 290° at around 21:15 BST, to find the planet shining at mag -0.8 just to the east of the Pleiades (+1.5). Take great care to avoid the glare of the Sun when looking for Mercury at sunset
  • At the start of the week the Waning Moon will appear in close proximity to Saturn (mag +0.7) and Jupiter (-2.2) in the southeastern pre-dawn sky
  • The Moon is Last Quarter on Monday
  • The Sun currently has one active region, AR 2818 and one emerging region on the oncoming limb that may develop into an active regtion. The sunspot number is 11
  • There are no visible ISS evening passes this week
in What's Up