September 2023 – What’s Up!

Week of 25th September

  • Astronomical twilight ends at 20:52 BST at the start of the week and at 20:37 BST by the end of the week.
  • Saturn (mag +0.5) lies at an altitude of about 15° in the southeast with Jupiter (-2.8) in the east, rising at around 20:10 BST, reaching a maximum altitude of 53° as it transits at around 03:45 BST.
  • Neptune (+7.8) lies 25° east of Saturn and Uranus (+5.7) is 8° east of Jupiter.
  • The Moon is Full on Friday – the Harvest Supermoon
  • The Sun currently has 12 active regions and the sunspot number is 198.
  • There are multiple visible evening ISS passes this week.
    (For full details about ISS passes click this link: heavens-above-iss-passes to visit the heavens-above website. If you are not in Marlborough, please ensure that you set your location for the most accurate ISS timings).

Week of 18th September

  • Astronomical twilight ends at 21:10 BST at the start of the week and at 20:54 BST by the end of the week.
  • The September equinox is on Saturday, marking the first day of autumn here in the northern hemisphere. The Sun will cross the celestial equator, decreasing in declination. Day and night length will be almost exactly equal and the Sun will rise due East and set due West, one of only two days in the year when this occurs.
  • The Planets: Mercury (-0.3) is at Greatest Western Elongation on Friday, Venus (-4.5) dominates the morning sky, Mars is too close to the Sun to be visible, Saturn (+0.5) culminates at 23:30 BST, Jupiter (-2.7) rises at 20:40 BST, Uranus (+5.7) lies about 7° east of Jupiter, and Neptune (mag +7.8) reaches opposition on Tuesday.
  • The Moon is First Quarter on Friday
  • The Sun currently has 6 active regions and the sunspot number is 88.
  • There are multiple visible evening ISS passes this week.
    (For full details about ISS passes click this link: heavens-above-iss-passes to visit the heavens-above website. If you are not in Marlborough, please ensure that you set your location for the most accurate ISS timings).

Week of 11th September

  • Astronomical twilight ends at 21:29 BST at the start of the week and at 21:13 BST by the end of the week.
  • Comet C/2023 P1 (Nishimura) passes perigee (its closest point to Earth) on Tuesday. The comet is reported to be visible by naked eye, though hard to spot. Look to the northeast, close to the horizon around sunrise (which is at about 06:30 BST this week) or in the northwest around sunset (19:30 BST). You will need a clear horizon as the comet is at an altitude of only 10°. [CAUTION: beware of bright sunlight in this area of the sky, especially if using binoculars or a telescope].
  • If out comet hunting at dawn, you will certainly see Venus (mag -4.5) at around 26° altitude in the east. A telescope will reveal its crescent phase as it moves towards greatest western elongation on 23rd October.
  • Saturn (+0.5) and Jupiter (-2.7) are both clearly visible in our south / southeastern evening sky.
  • The Moon is New on Friday
  • The Sun currently has 6 active regions and the sunspot number is 119.
  • There are multiple visible evening ISS passes this week.
    (For full details about ISS passes click this link: heavens-above-iss-passes to visit the heavens-above website. If you are not in Marlborough, please ensure that you set your location for the most accurate ISS timings).

 

Week of 4th September

  • Astronomical twilight ends at 21:49 BST at the start of the week and at 21:32 BST by the end of the week.
  • Saturn (mag +0.4) is well placed in the south, culminating at around midnight this week. Its brighter moons, such as Titan, Rhea and Iapetus can be easily observed in the same plane as the ring system.
  • Jupiter (-2.6) is rising ever earlier, now in our evening sky at around 21:30 BST. The Great Red Spot is perfectly placed for observation on Thursday evening.
  • Deep Sky hunters can find two globular clusters in the southern evening sky: Messier 2 (+6.5) in Aquarius and Messier 15 (+6.2) in Pegasus. Their distances from Earth are 38 and 34 thousand light years respectively.
  • The Moon is Last Quarter on Wednesday
  • The Sun currently has 5 active regions and the sunspot number is 77.
  • There are no visible evening ISS passes this week.
    (For full details about ISS passes click this link: heavens-above-iss-passes to visit the heavens-above website. If you are not in Marlborough, please ensure that you set your location for the most accurate ISS timings).

 

 

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