September 2021 – What’s Up!

Week of 12th September

  • Astronomical twilight ends at 21:22 BST at the start of the week and at 21:06 BST by the end of the week
  • Neptune reaches opposition on Tuesday, when it will be opposite the Sun as seen from Earth. It will be best placed for observation, appearing at its brightest, though still faint at mag +7.8, so binoculars or a telescope will be needed to see the planet. Look southeast in the constellation of Aquarius through the evening
  • Saturn (mag +0.4) and Jupiter (-2.8) continue to dominate our evening skies. They will be joined by the waxing Gibbous Moon towards the end of the week
  • The Moon is First Quarter on Monday
  • The Sun currently has 5 active regions: AR2863, AR2864, AR2866, AR2868 and AR2869. The sunspot number is 93
  • The ISS makes multiple visible evening passes this week as follows:
    Thursday: 21:27, SW to SSW, max 14°
    Friday: 20:41, SSW to SSE, max 23°
    Saturday: 19:57, S to ESE, max 17° & 21:32, WSW to SW, max 31°
    Sunday: 20:47, SW to ESE, max 46°

Week of 6th September

  • Astronomical twilight ends at 21:42 BST at the start of the week and at 21:25 BST by the end of the week
  • On Thursday evening, spot the 3 day old waxing Crescent Moon just under 7° from Venus (mag -4.1) as they set in the West. Look just after sunset, which is at 19:34 BST
  • Jupiter (-2.8) and Saturn (+0.3) are well placed in our evening skies
  • With little to no moonlight, this week is the perfect opportunity to observe M27, the Dumbbell Nebula, a planetary nebula in the constellation of Vulpecula, just below Cygnus. At mag +7 and only 8 arcminutes in size, you will need a good pair of binoculars or a telescope to find it
  • The Moon is New on Tuesday
  • The Sun currently has 5 active regions, AR2863, AR2864, AR2865, AR2866 and AR2867. The sunspot number is 68
  • There are no visible evening ISS passes this week