July 2023 – What’s Up!

Week of 31st July

  • Astronomical twilight ends at 23:49 BST at the start of the week and at 23:24 BST by the end of the week.
  • On Thursday, Saturn (mag +0.6) and the Waning Gibbous Moon (-11.0) will be separated by just 7°. Saturn will rise first at about 22:00 BST, followed by the Moon some 15 minutes later.
  • If you have a reasonably low southern horizon, go Wild Duck hunting this week! M11, the Wild Duck Cluster, is well placed for observation with binoculars as it is due south at around 23:00 BST, but being in the constellation of Scutum, just below Aquila, it only reaches about 30° altitude. Whilst in that area, enjoy the plethora of open clusters in the Milky Way.
  • The Moon is Full on Tuesday – the Sturgeon Moon. This is the first of two Full Moons in August, so the second one, on the 31st, will be a ‘Blue Moon’.
  • The Sun currently has 10 active regions and the sunspot number is 147.
  • 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).

 

Week of 24th July

  • Astronomical twilight ends at 00:31 BST at the start of the week and at 23:53 by the end of the week.
  • Mercury (mag -0.1) reaches its highest altitude in the evening sky on Tuesday. Look about 8° above the western horizon just after sunset (21:05 BST) to see the small planet about 5° above and to the west of Venus (-4.4). A telescope will show Mercury in its waning gibbous phase and Venus as a thin crescent at just 10% illumination.
  • Saturn (+0.6) is returning to our evening skies, rising at around 22:15 BST this week. It culminates at about 03:00 BST, reaching a maximum altitude of 27°. The ringed planet reaches opposition on 27th August, when it will be best placed for observation.
  • The Moon is First Quarter on Tuesday.
  • The Sun currently has 6 active regions and the sunspot number is 103.
  • 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 17th July

  • Darkness finally returns on Thursday night when astronomical twilight ends at 01:05 BST on Friday morning, only to start again at 01:22, giving us just 17 minutes of proper astronomical darkness!
  • Dwarf planet Pluto reaches opposition on Saturday. It will still be tricky to spot at just 0.1 arcsecond in apparent size and magnitude +14.3. Further to this, it only reaches 15° of altitude as it culminates at 01:12 BST. A hard target to find, but a satisfying catch if successful.
  • The New Moon provides sufficient darkness to hunt down faint nebulae in Cygnus this week. The first is NGC 7000, the North American Nebula close to Deneb. This contrasting patch of gas and dust is mag +4.0 and covers about 2° of sky, so low power is recommended. The more challenging Veil Nebula (NGC 6995, 6974 & 6960) is a faint supernova remnant at around mag +5, stretching about 3°. It is notoriously difficult to observe visually, so only the darkest skies and largest optics will do.
  • The Moon is New on Monday.
  • The Sun currently has 6 active regions and the sunspot number is 96.
  • 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 10th July

  • Astronomical twilight does not end until July 21st.
  • Keep an eye out for noctilucent clouds; they have been illusive so far this season, but reports indicate that they are starting to appear now. Look to the northern horizon after sunset and before sunrise for these high altitude, night shining opalescent clouds.
  • Search for two planetary nebulae in the Summer Triangle this week. The first is M57, the Ring Nebula in Lyra (mag +8.8), and the second is M27, the Dumbbell Nebula in Vulpecula (+7.1). You will need a telescope to find these remnants of exploded low mass stars. A high contrast filter can help tweak out more detail.
  • The Moon is Last Quarter on Monday.
  • The Sun currently has 11 active regions and the sunspot number is 197.
  • 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 3rd July

  • Astronomical twilight does not end until July 21st.
  • The Earth reaches aphelion on Thursday, the most distant point from the Sun in its elliptical orbit, at a distance of 1.017 AU or a little over 152 million kilometres.
  • Despite the Full Moon this week, which is very low in the sky, reaching a maximum altitude of only 13°, it will still be possible to find some of the brighter deep sky objects. Track down two Globular Clusters in the Summer Triangle: M56 (mag +8.8) in Lyra and M71 (+8.1) in Sagitta.
  • The Moon is Full on Monday – the Buck Moon.
  • The Sun currently has 7 active regions and the sunspot number is 119.
  • 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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