January 2020 What’s Up!

Week of 27th January

• Astronomical twilight ends at 18:44 UT at the start of the week and 18:53 UT at the end
• There is an unusual conjunction of Neptune (mag +8) and Venus (mag -4) on Monday evening. Look low in the southwest sky between 17:00 and 19:30 UT to see the two planets just 4 arcminutes apart. You will need to use a pair of binoculars or a telescope to observe the conjunction. On Tuesday evening, the Crescent Moon comes within 4 degrees of the pair, making an interesting combination to look out for
• The Moon is waxing and will be First Quarter on Sunday
• Look to the southwest just after sunset to see Venus dominate the twilight sky at mag -4.0
• The Sun has one Cycle 24 active region near the equator (AR 2757). A region of interest belonging to Cycle 25 is developing high in latitude around the southeast limb
• There are multiple visible evening ISS passes this week as follows:
  Monday: 18:14, WSW to E, max 72°
  Tuesday: 17:26, WSW to E, max 57° & 19:03, W to WNW, max 70°
  Wednesday: 18:16, W to E, max 87° & 19:52, W, max 20°
  Thursday: 17:28, WSW to E, max 85° & 19:05, W, max 73°
  Friday: 18:17, W to E, max 86° & 19:54, W, max 20°
  Saturday: 17:30, W to E, max 84° & 19:07, W to SSW, max 60°
  Sunday: 18:19, W to ESE, max 75° & 19:56, W to WSW, max 18°

Week of 20th January

• Astronomical twilight ends at 18:34 UT at the start of the week and 18:42 UT at the end
• Betelgeuse continues to appear dimmer than its normal magnitude of +0.5. Compare with Rigel (+0.3) and Bellatrix (+1.6). The lower brightness is only in the visible wavelengths, in infrared it continues to shine as brightly as ever
• The Moon is waning and will be New on Friday
• Venus continues to dominate the western evening twilight sky at mag -4.0
• The Sun has no spots, with a current spotless stretch of 7 days
• There are multiple early evening ISS passes this week as follows:
  Wednesday: 18:59, SW to S, max 25°
  Thursday: 18:11, SSW to ESE, max 23°
  Friday: 17:24, S to E, max 16° & 18:59, WSW to SSW, max 47°
  Saturday: 18:11, SW to E, max 42°
  Sunday: 17:23, SSW to E, max 31° & 18:59, WSW, max 70°

Week of 13th January

• Astronomical twilight ends at 18:25 UT at the start of the week and 18:32 UT at the end
• Betelgeuse, the red giant star at Orion’s left shoulder, has dimmed significantly since the autumn. Normally it shines at magnitude +0.4, but it is currently at mag +1.4, about two and a half times dimmer. Compare its brightness with the star at Orion’s right heel, Rigel, which is mag +0.3 and the difference is very clear. Many theories about what is causing the change abound, but the most widely accepted is that Betelgeuse, as a variable star, is experiencing a period of swelling, which leads to its luminosity being spread across a larger surface area, therefore appearing dimmer to us
• The Moon is waning and will be Last Quarter on Friday
• Venus continues to dominate the evening twilight sky at mag -4.0
• The Sun is currently spotless again after a recent period of increased activity
• There are no evening ISS passes this week

Week of 6th January 2020

• Astronomical twilight ends at 18:17 UT at the start of the week and 18:23 UT at the end
• Watch The Sky at Night at 10pm on BBC4 next Sunday (12th) to see CEB and observing on the College playing fields feature
• There is a penumbral Lunar eclipse on Friday 10th as the Full Moon passes through the faint outer edge of the Earth’s shadow (the penumbra). Maximum eclipse occurs at 19:11. It will not be very obvious to the naked eye, but comparative photos will show the difference
• The Moon is waxing and will be Full on Friday
• Venus continues to dominate the evening twilight sky
• The Sun has one, reversed polarity, Cycle 25, active region (AR2755)
• There are no evening ISS passes this week