April 2021 What’s Up!

Week of 26th April

• Astronomical twilight ends at 22:44 BST at the beginning of the week and at 23:04 BST by the end of the week
• On Tuesday the Moon reaches perigee, the closest point to Earth along its orbit. It will be at a distance of about 357,000 km with an angular size of 33.42 arcminutes, compared to its average size of 31.07 arcminutes. Perigee coincides with the full Moon, making it a ‘super Moon’, the first of three this year
• The Moon is Full on Tuesday – the Super Pink Moon. Named ‘Super’ as it is a super Moon and ‘Pink’ after the early seasonal arrival of a species of wildflower in northern Native American culture
• The Sun currently has multiple active regions, AR 2816, 2818, 2819 and 2820. The sunspot number is 62. There is a significant increase in activity so far this year compared to 2020
• There are no visible ISS evening passes this week

Week of 19th April

• Astronomical twilight ends at 22:24 BST at the beginning of the week and at 22:41 BST by the end of the week
• The Lyrid meteor shower peaks on Thursday afternoon. Look out for increased meteor activity on both Wednesday and Thursday nights. The predicted Zenithal Hourly Rate is only 18, so don’t expect an intense display and viewing will be further hampered by the waxing Gibbous Moon. Hopefully the Radio Meteor Detector will pick up the increased activity. The Lyrid meteors are created by debris left behind by comet C/1861 G1 (Thatcher)
• The Moon is First Quarter on Tuesday
• The Sun currently has two active regions, AR 2814 and AR 2816. The sunspot number is 28. Recent data on sunspot count and solar activity suggest that the new Solar Cycle 25 is intensifying more quickly than originally predicted and the peak could be in 2024 rather than 2025
• There are no visible ISS evening passes this week

Week of 12th April

• Astronomical twilight ends at 22:05 BST at the beginning of the week and at 22:21 BST by the end of the week
• On Saturday the 27% waxing Crescent Moon will appear close to Mars, with a separation of just under 4°. Look in the West after sunset to find the pair
• The Moon is New on Monday
• The Sun currently has no visible active regions. The spotless stretch is 4 days
• There are no visible ISS evening passes this week

Week of 5th April

• Astronomical twilight ends at 21:48 BST at the beginning of the week and at 22:03 BST by the end of the week
• For the early risers, look low to the southeastern horizon from around 05:30 BST for about an hour before sunrise to find the waning Crescent Moon. On Tuesday morning it will be in conjunction with Saturn (mag +0.8) and on Wednesday morning it will be in conjunction with Jupiter (-2.1)
• The Moon is a waning Crescent all this week
• The Sun has one emerging potential active region in the Northern Hemisphere. It has been increasingly active so far this year, with only 36 spotless days, that being 38%; compare this to 57% spotless days last year and 77% the year before
• There are no visible ISS evening passes this week