August 2021 – What’s Up!

Week of 30th August

  • Astronomical twilight ends at 22:03 BST at the start of the week and at 21:45 BST by the end of the week
  • On Wednesday, Mercury (mag 0.0) reaches its highest point in the evening sky. It will be at 5° above the western horizon at sunset (19:52 BST). Take care of the setting Sun if searching for the planet, especially if using binoculars. Venus (-4.0) can be found 15° further East at about 9° altitude
  • Saturn (mag +0.3) and Jupiter (-2.9) are well placed for observation in our evening sky this week, with Saturn culminating at 23:04 BST and Jupiter an hour later. To complete the suite of planets, find Neptune (+7.8) and  Uranus (+5.7) further East along the ecliptic
  • The Moon is Last Quarter on Monday
  • The Sun currently has 4 active regions, AR2859, AR2860, AR2861 and AR2862. The sunspot number is 77
  • There are no visible evening ISS passes this week

Week of 23rd August

  • Astronomical twilight ends at 22:24 BST at the start of the week and at 22:06 BST by the end of the week
  • Venus makes a brief appearance in our western evening sky around sunset, shining at magnitude -4.0, but has set itself by 21:20 BST
  • Four more planets are on view through the night, with, from West to East, Saturn (mag +0.3), followed by Jupiter (-2.9), then Neptune (+7.8) and finally Uranus (+5.7), which rises at 22:19 BST
  • The Moon is waning Gibbous all week, not reaching Last Quarter until next Monday
  • The Sun currently has 2 active regions, AR2858 and AR2859. The sunspot number is 25
  • There are no visible evening ISS passes this week

Week of 16th August

  • Astronomical twilight ends at 22:47 BST at the start of the week and at 22:28 BST by the end of the week
  • Jupiter reaches opposition on Thursday. In this celestial position, opposite the Sun for us on Earth, it is best placed for observation, being at its brightest (mag -2.9) and largest with an apparent size of 49 arcseconds. This is the perfect time to train binoculars or a telescope on the Gas Giant, which you will find in the southeastern evening sky
  • On Sunday, Jupiter rises at 20:06 BST in the east-southeast with a double moon transit in progress. Two of its Galilean moons, Europa and Ganymede, will be crossing in front of the planet and their shadows will also be visible on the planet’s surface. The event ends when Ganymede’s shadow leaves the disc at 23:20 BST
  • The Moon is Full on Sunday – the Sturgeon Moon. It is the third of four Full Moons in the period from the summer solstice to the autumn equinox and as such, is called a Blue Moon
  • The Sun currently has 4 active regions, AR2853, AR2855, AR2856 and AR2857. The sunspot number is 47
  • There are no visible evening ISS passes this week

Week of 9th August

  • Astronomical twilight ends at 23:11 BST at the start of the week and at 22:50 BST by the end of the week
  • On Wednesday evening, the 3 day old waxing crescent Moon will make a close approach to Venus (mag -4.0), appearing with just 5° of separation low in the western sky just after sunset
  • The Perseid meteor shower peaks on Thursday night, with a maximum zenithal hourly rate of around 150 meteors per hour, making it one of the most active showers of the year. The favourable Moon phase makes for optimum observing conditions through the night. The shower runs from 14th July to 24th August, so meteors can be spotted throughout that period. The shower is created by debris from comet 109P/Swift-Tuttle
  • Saturn (+0.2) and Jupiter (-2.9) continue to adorn our evening skies in the southeast
  • The Moon is First Quarter on Sunday
  • The Sun currently has no active regions. The spotless stretch is 2 days
  • There are no visible evening ISS passes this week

Week of 2nd August

  • Astronomical twilight ends at 23:38 BST at the start of the week and at 23:15 BST by the end of the week
  • Saturn reaches opposition on Monday, when it lies opposite the Sun in the sky. It is best placed for observation at this time as it appears at its largest and brightest at 18.6 arcseconds in apparent size and magnitude +0.2. At opposition, Saturn’s rings show a discernible brightening, known as the Seeliger Effect
  • Jupiter is about 20° further East in the southeastern evening sky, shining at magnitude -2.8
  • The Moon is New on Sunday
  • The Sun currently has no active regions. The spotless stretch is 4 days
  • There are no visible evening ISS passes this week

 

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