What’s Up! October 2021

A monthly look at astronomical events in the sky and on Earth 

Compiled by Steve Sawyer

A slightly later bulletin this month. I’m standing in for John Rowland, hopefully doing a decent job!

There are some interesting events taking place this month.  The primary events are Jupiter’s moon transits, 2 meteor showers and the appearance of Nessie on the moon!

The Sky at night on BBC 4 10th October 10 PM covers the forgotten solar system.  Neptune and Uranus have only ever been visited once by Voyager 2 but there are opportunities for further missions.

For those interested in Astrophotography the results of the Astronomy Photographer of the year have been announced, with some stunning images.

Tibetan Solar Eclipse 2020

Fig1 Astro Winner

Tibetan Solar Eclipse 2020

2021-10_Fig2_astro_2

Fig2 Astro 2

I really like this one (Fig.2). Venus rising over the moon. For more information, go to RMG Astronomy Photographer of the Year. [Don’t forget to put clocks back on the 31st October!]

 

October Objects

The Sun

There are currently 28 sunspots on the sun. Sunspot AR2877 has a ‘beta-gamma’ magnetic field that harbours energy for M-class solar flares. Sunspot AR2880 has a simpler, more stable magnetic field, unlikely to flare.  Some very good dashboards for space weather enthusiasts can be found at Space Weather Prediction Center.

 

The Moon

On Thursday the 7th a very thin 2%-lit waxing crescent Moon may be seen low above the west southwest horizon. The weather forecast is currently quite good so this might be possible to see! (See the Crescent Moon Watch page for more details.)

 

On Wednesday the 13th an unusual effect will occur around 19:45 PM with the crater Ptolemaeus. The shadows cast by the sun create an unusual shadow shape that is like the famous photo of Nessie.

2021-10_Fig3_nessie

Fig3 The Nessie

2021-10_Fig4_moon1 2021-10_Fig5_moon2

As the sky darkens after sunset on Saturday, 9th October, watch the southwestern sky for the pairing of the slim crescent moon shining just above a very bright Venus – easily close enough for them to share your binoculars’ field of view.  It may be possible to spot the moon in the late afternoon and also see Venus’ bright speck below it.  Once the sky darkens, the fainter claw stars of Scorpius will appear around the moon and Venus.

 

On Thursday the 28th the last quarter moon rises around 23:30. Once risen try to spot the Beehive cluster slightly to the south-southwest (2.7 degrees).   A pair of 7×50 binoculars will fit both objects in the same field of view.

 

The Planets

Mercury

The best viewing is on the 25th from 1 hour prior to sunrise.  The first sighting is possible on the 18th October when the planet rises 90 minutes before the sun and shines at mag +0.9.  The planet is very low on the horizon (7 degrees) so you’ll need a good unobstructed viewpoint.

 

Venus

The evening planet remains low after sunset. Best time to see it is the 28th of October.

 

Mars

Mars is in conjunction with the sun this month and is not visible.

 

Jupiter

A rare double transit of Ganymede and Callisto shadows occurs on the evening of 4th  October 2021.

Fig Jupiter

Also just after midnight on the 20th October, it’s possible to see both Io and Callisto in transit at the same time.  This starts at 00:30 on 21st October.

 

Saturn

Evening planet, reaching highest altitude early evening. A waxing gibbous Moon near on 13-14 October.

 

Uranus

Remains well-positioned all month. Currently in Aries and is shining at mag +5.7 which means it could be visible to the naked eye with good dark skies. Currently, Uranus is the best planet to observe from the UK.  Although very small its greenish disc will be visible to smaller telescopes and larger scopes should be able to resolve some of the planet’s banding as well as some of the brighter moons.

 

 Neptune

Uranus is still a morning object and best seen after its opposition in November.  Neptune reaches opposition on the 14th so is well placed for observing, but you might like to wait until mid-October, when it’s highest in the sky (30+°) earlier in the evening (about 2300).

 

Meteor Showers

There are two showers this month.  The Draconids on the 8th October from around 20:30 PM, with around 5+ meteors per hour.  Followed by the Orionids shower which takes place on the 21st of October.  However, this will be spoiled by a just past full moon which may wash out many of the fainter trails.

 

Deep Sky Objects

Some targets for this month

 

M33 

M33 is a large but faint spiral galaxy in Triangulum.  Mag 5.7 is hard to see as its surface brightness is low.

 

NGC 869

The open star cluster NGC 869 (mag 4.0) in Perseus, also known as the western half of the double cluster, will be well placed, high in the sky. It will reach its highest point in the sky at around midnight local time.

 

NGC 884

The open star cluster NGC 884 (mag 4.0) in Perseus, also known as the eastern half of the double cluster, will be well placed, high in the sky. It will reach its highest point in the sky at around midnight local time.

 

Last Month’s Challenge – Name the Star

The name of the star from the Wikipedia List of Brightest Stars (which is 93 stars long) using the first letter of the first names of a few famous astronomers (as given in the What’s Up September 2021 issue) was “Alpheratz” and the winner is Andrew Downie.

 

This Month’s Challenge – Interstellar Journey

2021-10_Fig7_Sky_Image

Fig7 Sky Image

You are the navigation officer of an interstellar spacecraft that left Earth in 2050 on an 11-year (spacecraft time) mission to explore a distant star system and has now returned to Earth. (Thanks to a remarkable discovery by a teenager from Upton Snodsbury, Worcestershire working in his dad’s garage on a power booster for his jump-and-glide pogo stick, speeds approaching the speed of light are now possible.) Unfortunately, due to a major malfunction of the computer-controlled communication, navigation and landing systems, your spacecraft has ended up floating (thanks to its buoyancy bags) somewhere in the ocean. It is clear but dark and you have no idea where you are or even what date it is. You open the hatch and look around. A beautiful waxing gibbous moon is reflected in the gently lapping water. Some way off, a whale sends a plume of spray up from its blowhole then silence returns as it disappears into the deep. As for the sky, In one direction you see the view shown below. You use a sextant to measure the altitude of three stars. It’s a difficult job but you reckon Regulus is at 11¼°, Arcturus is at 18½° and Altair is at 9¼°.

 

  1. Where are you?
  2. What’s the date?

 

All general comments about this What’s Up are welcome and will be published immediately after moderation. But if they give or hint at the answer to the challenge, they will be published on the 15th.

 

Thanks for your interest, and I wish you clear skies and good viewing. Stay safe!

Steve on behalf of John Rowland!

2 thoughts on “What’s Up! October 2021

  1. Thanks Steve for stepping in to cover the What’s Up this month – useful and informative as always. I was disappointed to not have a chance of seeing the double shadow transit last night (4th) though – was hopeful for that one but grim weather for astronomy here!

  2. Good info as usual. Thanks Steve.
    The challenge is a bit mind bending for me –
    To misquote Gandalf “This foe is beyond me (any of you). Run!”
    Neil Moss

Leave a Reply to Neil Moss Cancel reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.