April 2023 – What’s Up!

Week of 24th April

• Astronomical twilight ends at 22:37 BST at the beginning of the week and at 22:56 BST by the end of the week.
• Venus (mag -4.1) will be at its highest altitude in our evening sky on Friday. Just after sunset, at 20:30 BST, it will be 33° above the western horizon.
• This week’s Deep Sky Challenge is M104, a spectacular galaxy in the constellation of Virgo, the Sombrero Galaxy. It is a tough target to spot at mag +8 and is at quite a low altitude of only 26° when it culminates, but is well worth hunting down with a telescope. If you succeed, you will be viewing light that has taken 28 million years to reach you!
• The Moon is First Quarter on Thursday.
• The Sun currently has 6 active regions and the sunspot number is 87.
• There are no visible evening ISS passes this week.

Week of 17th April

• Astronomical twilight ends at 22:17 BST at the beginning of the week and at 22:34 BST by the end of the week.
• As bright Venus (-4.1) sets in the west through this week, the New Moon gives perfect dark skies to go galaxy hunting. A telescope will be needed to track down ‘faint fuzzies’ in Leo, Virgo and Coma Berenices such as M87 (+8.7) or M104 (+8.1). For an easier target, try M3 (+6.2), a beautiful globular cluster a little further east in Canes Venatici.
• There is a hybrid solar eclipse on Thursday, though it won’t be visible from Marlborough, only observers around Indonesia will be treated to this spectacle.
• The Lyrid meteor shower peaks on Saturday night, but it is not a particularly productive shower, with only around 18 meteors per hour expected. It is noteworthy as one of the oldest recorded meteor showers, featuring in ancient Chinese texts from around 2500 years ago. The shower’s progenitor is comet C/1861 G1 (Thatcher).
• The Moon is New on Thursday.
• The Sun currently has 8 active regions and the sunspot number is 151.
• There are no visible evening ISS passes this week.

Week of 10th April

• Astronomical twilight ends at 21:59 BST at the beginning of the week and at 22:15 BST by the end of the week.
• Mercury (mag -0.1) reaches Greatest Eastern Elongation on Tuesday, when it will be at its furthest separation from the Sun, appearing about 16° above the western horizon just after sunset.
• Venus (-4.1) will appear next to the Pleiades (M45) on Tuesday, separated by just 2° from the Open Cluster, neatly fitting into the field of view of a pair of low power binoculars.
• On Thursday, ESA’s JUICE mission is set to lift off from French Guiana at 12:15 UT. The Jupiter Icy Moons Explorer (JUICE) will take 8 years to reach the Jupiter system, where it will visit Callisto and Europa before entering a permanent orbit around Ganymede.
• The Moon is Last Quarter on Thursday.
• The Sun currently has 2 active regions and the sunspot number is 52.
• There are no visible evening ISS passes this week.

Week of 3rd April

• Astronomical twilight ends at 21:43 BST at the beginning of the week and at 21:57 BST by the end of the week.
• Venus (mag -4.0) continues to dominate our early evening sky. It is at an altitude of about 29° above the western horizon just after sunset. A telescope will show Venus in its Gibbous phase.
• Observing highlights this week will be affected by the bright Moon, but more westerly open clusters such as M48 in Hydra and M44 in Cancer are still worth hunting down with binoculars or a telescope.
• The Moon is Full on Thursday – the Pink Moon.
• The Sun currently has 8 active regions and the sunspot number is 23.
• There is one visible evening ISS pass this week:
  Monday: 20:22 (-1.0) WSW, max 12°