September 2024 – What’s Up!

Week of 30th September

  • Astronomical twilight ends at 20:37 BST at the start of the week and at 20:23 BST by the end of the week.
  • Look for Comet C/2023 A3 (Tsuchinshan-ATLAS) (mag +2.9) in our morning sky, visible in the east, low to the horizon just before dawn. It will become an evening object, visible in the west from about 12th October.
  • There is an annular solar eclipse on Wednesday, but only visible from Chile and Argentina; follow the landfall totality online between 20:23 UTC and 20:28 UTC.
  • Saturn (+0.7) culminates at around 23:20 BST through this week and its edge on alignment makes for some interesting moon transits. Rhea crosses the planet on Monday evening, starting at 19:30 BST.
  • The Moon is New on Wednesday.
  • The Sun currently has 9 active regions and the sunspot number is 148.
  • There are no visible evening ISS passes this week (click here for full ISS pass details).

Week of 23rd September

  • Astronomical twilight ends at 20:55 BST at the start of the week and at 20:40 BST by the end of the week.
  • Saturn (+0.6) has now passed opposition, but remains a magnificent sight in the evening sky. It culminates at around 00:00 BST. How many of its moons can you spot through a telescope?
  • Comet C/2023 A3 (Tsuchinshan-ATLAS) passes perihelion on Friday, when it will be 0.4 AU from the Sun. It is currently only visible from the Southern Hemisphere, but the images are impressive as the comet is about magnitude +4. It will be in our evening sky from the middle of October – updates to follow.
  • The Moon is Last Quarter on Tuesday.
  • The Sun currently has 7 active regions and the sunspot number is 117.
  • There are multiple visible evening ISS passes this week (click here for full ISS pass details).

Week of 16th September

  • Astronomical twilight ends at 21:16 BST at the start of the week and at 20:58 BST by the end of the week.
  • The September Equinox is on Sunday. This is the beginning of Astronomical Autumn for the Northern Hemisphere. Day length and night length will be equal and the Sun will rise due East and set due West, one of only two days in the year when this happens!
  • For the early risers, there is a partial lunar eclipse on Wednesday. Maximum eclipse is at 03:45 BST, when 8% of the lunar surface will be covered by the Earth’s shadow or umbra.
  • Neptune (+7.8) reaches opposition on Saturday when it will be a mere 28.89 AU away; it will be best placed for observation reaching a maximum apparent size of 2.4 arcsec. Look for the distant Ice Giant about 13° to the east of Saturn (+0.6) in the constellation of Pisces.
  • The Moon is Full on Wednesday – the Harvest Supermoon.
  • The Sun currently has 7 active regions and the sunspot number is 136.
  • There are multiple visible evening ISS passes this week (click here for full ISS pass details).

Week of 9th September

  • Astronomical twilight ends at 21:33 BST at the start of the week and at 21:16 BST by the end of the week.
  • Saturn (+0.6) is well placed for observation as it culminates at around 01:00 BST this week.
  • Search for members of our Local Group of Galaxies in the relative darkness this week. Find M31, the Andromeda Galaxy (+3.3) in Andromeda at about 2.5 million light years from Earth. It is the most distant object observable by naked eye, but you will need a good dark site to spot it without an instrument. Through a telescope, look for its satellite galaxies, M32 (+7.9) and M110 (+8.1). Move 15° south into Triangulum to find M33, the Triangulum or Pinwheel Galaxy (+5.8) at 2.8 mly; it is very diffuse, so hard to make out. It is the third largest galaxy of the Local Group after M31 and the Milky Way.
  • The Moon is First Quarter on Wednesday.
  • The Sun currently has 10 active regions and the sunspot number is 179.
  • There are multiple visible evening ISS passes this week (click here for full ISS pass details).

Week of 2nd September

  • Astronomical twilight ends at 21:53 BST at the start of the week and at 21:36 BST by the end of the week.
  • Saturn (+0.6) reaches opposition on Sunday, making it best placed for observation as it appears largest and brightest in our evening sky. Find the planet in Aquarius. It culminates at around 01:30 BST this week.
  • Jupiter (-2.3) and Mars (+0.7) are morning objects as they progress towards opposition, which Jupiter reaches on 7th December, and Mars on 16th January. Mercury reaches Greatest Western Elongation on Thursday and can be seen about 10° above the eastern horizon just before sunrise.
  • This week we move to Cassiopeia and Perseus to find three fabulous open clusters. First up is Caroline’s Rose, NGC 7789 at mag +6.7, then on to the Owl Cluster, NGC 457 (+6.4), and finishing with the Double Cluster, NGC 869 (+5.3). All are at around 6,000 light years from Earth and will need binoculars or a telescope to observe.
  • The Moon is New on Tuesday.
  • The Sun currently has 11 active regions and the sunspot number is 180.
  • There are no visible evening ISS passes this week (click here for full ISS pass details).

 

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