The night sky in August 2020

posted 29 Jul 2020, 13:53 by Pete Collins
by Anne Holt

Sunrise       1st:  05.25         31st:  06.17
Sunset        1st:  21.05         31st:  20.00

Astronomical darkness
1st:   00.33 to 01.57       31st:  22.13 to 04.05

Day length   1st:  15.38.45        31st:  13.42.56

Full Moon:  3rd at 16.58     New Moon:  19th at 03.41

Lunar apogee:   9th at 10.52  (404657 km)
Lunar perigee:  21st at 11.00  (363512 km)

August's Full Moon is known as the Sturgeon Moon because this is the time when they were plentiful in the lakes where the Algonquin fished.  Other Native American tribes had different names - to the Sioux it was the Moon When All Things Ripen, the Chocktaw called it the Women's Moon, for the Cherokee it was the Fruit Moon and for many other tribes it was the Red Moon, as it often took on a reddish hue when seen through the summer haze. Other names are the Green Corn Moon,  the Barley Moon, the Old English / Anglo Saxon Grain Moon, the Chinese Harvest Moon and the Celtic Dispute Moon.

Highlights

Astronomical darkness increases considerably during August, on 1st we have 1 hour 24 minutes, increasing to almost 6 hours by the end of the month.  Venus is still shining brightly in the morning sky and Jupiter and Saturn are visible before midnight, unfortunately still very low.  Mars rises a little later but gets much higher in the morning sky. Comet C/2020 F3 (NEOWISE) is fading rapidly and is now very low at dusk.  Two more faint comets are in the same area of sky,  one of them is now getting higher, all end the month at around mag 10.
The main highlight, as in every August, is the Perseid meteor shower, marred again this year by the Moon rising around midnight.

Constellations

When it finally gets dark enough, the Milky Way is now at its best.  From a dark sky site it can be seen stretching right across the sky and down to the southern horizon, passing almost overhead around midnight.

The Milky Way passes through the Summer Triangle, which is now high in the sky, with Deneb and Vega particularly prominent.  Alberio, a beautiful yellow and blue double star at the head of Cygnus the swan, is very well placed for telescopic observation.

The Plough and its host constellation Ursa Major are now very low in the Northern sky which means that the W asterism of Cassiopeia is riding high in the south east and very easy to spot.

Pegasus and Andromeda are now well above the horizon for most of the night and Perseus, followed by Auriga, are rising soon after midnight.

Planets

Mercury:  in Gemini, mag -0.9
Not easy to see this month, on 1st it rises at 03.51 but is only 6 degrees above the horizon when the sky begins to brighten. It moves into Cancer on  5th and reaches perihelion on 6th.  At this time, because of its highly elliptical orbit, it gets twice as much heat and light from the Sun than it does when it's at its furthest point.  On this day it rises at 03.51 but is still only 11 degrees by dawn. On 17th it reaches superior conjunction, on the opposite side of the Sun to the Earth.  Around this time it is at mag -2.0, but much too close to the Sun to be seen - only 1 degree 45' to the north at its closest.  It then becomes an evening object, still too low to be visible.  On 31st it sets at 20.24 and is just below the horizon at dusk.   

Venus:  in Taurus, mag -4.4
Fades slightly during the month but is still unmissable in the morning sky, getting slightly higher before the sky is too bright. On 1st it rises at 02.05 and should be easily visible an hour later, reaching 23 degrees in the east by dawn.  On 6th it moves into Orion and on 14th reaches greatest western elongation, separated from the Sun by 46 degrees. On this day it rises at 01.58 and gets to 27 degrees before the sky brightens. On 14th it crosses the border into Gemini and the following day is close to the 15% lit Moon.  At 5am the planet is 5.5 degrees to the SE, they are closest at 13.44, when the Moon passes 4 degrees to the north.  On 31st Venus is at mag -4.2, rising at 02.08 and reaching 30 degrees in reasonable darkness.

Mars:  in Pisces,  mag 1.1
Still improving in both brightness and position.  On 1st it rises at 23.14 and is at 23 degrees in the south when dawn breaks. It is at perihelion on 3rd, when its distance from the Sun is 1.38 AU.  At this time it gets 31% more radiation from the Sun than at aphelion.  On 9th the 73% Moon passes south of Mars, as the sky brightens they are 3 degrees apart, with Mars 41 degrees above the southern horizon. They are closest, in daylight, at 09.38 when the Moon is 41' to the south.  On 31st it rises at 21.34 and reaches its highest point, 43 degrees, at 04.18.  It will now be at mag -1.8.

Jupiter: In Sagittarius, mag -2.7
Still very bright, so should be easily visible despite its low altitude. On 1st it rises at 20.02 and culminates at 23.52,  only 14 degrees above the southern horizon.  On 2nd at 00.32 the almost full Moon passes 1 degree 3' to the south. The pair should be visible from around 21.30 on the night of 1st/2nd.  They are again close on the 28th/29th, at 22.00 the 83% Moon is 3.5 degrees to the SW.  They get closer during the night but are at their closest, 1 degree 24', after Jupiter has set for Manchester observers.  By 31st it is slightly fainter at mag -2.6, and is at 14 degrees in the south as the sky darkens, culminating at 21.43, only a couple of degrees higher.  Observers with a decent pair of binoculars and a clear southern horizon should be able to see the planet's disc and maybe the 4 Galilean moons.

Saturn:  in Sagittarius, mag 0.1
Now about 7.5 degrees to the east of Jupiter, much fainter but slightly higher than the larger planet.  On 1st Saturn rises at 20.24 and should be visible soon after 22.00, when it reaches 10 degrees in the SE.  It culminates at 00.28, at 15 degrees, and sets at 04.29.  On 2nd the 96% Moon passes 2 degrees 15' to the south at 14.29.  By 23.00 it will be 6 degrees SE of the planet.  On 29th the 87% Moon is 2 degrees 11' to the south at 17.59.  They should be visible soon after 22.00 when Saturn, now at its highest point, is 3 degrees 30' NW of the Moon.  On 31st Saturn rises at 18.21, culminating at 22.19 and setting at 02.21.  It will also have faded slightly, ending August at mag 0.3.

Uranus:  in Aries, mag 5.8
Visible in the early hours, its position improving during August.  On 1st it rises at 23.31 and reaches 32 degrees in the east by dawn.  On 31st it rises at 21.33 and gets to 50 degrees in the south by 04.45, as the sky begins to brighten.  As always, in order to see it with the naked eye, excellent eyesight and a very dark sky site are needed - as well as knowing exactly where to look.  It should be a fairly easy binocular target, again if you know where to look.  When seen through a scope the small disc has a greenish blue hue.

Neptune: in Aquarius, mag 7.8
Fainter and lower than Uranus but high enough for telescopic observation and imaging for much of the night, especially later in the month.  On 1st it rises at 22.14 and reaches 31 degrees in the south by 03.30.  On 31st it rises at 20.15 and culminates in astro darkness at 01.34, still at 31 degrees.  An amateur scope should show that the small disc is much bluer than that of Uranus.  A large telescope is needed to see the large moon Triton, at mag 13.5.

Dwarf Planets

Ceres: in Aquarius, mag 8.1
The closest and largest of the 5 dwarf planets - by far the largest body in the asteroid belt, and the first to be discovered - is not easy to see this month, as it remains low, even at opposition.  On 1st it rises at 23.35 and culminates, 15 degrees in the south, at 03.42.  It is at opposition on 28th, slightly brighter at mag 7.7 but even lower.  It reaches its highest point, only 12 degrees, at 01.23.

Pluto: in Sagittarius, mag 15.0
Despite being above the horizon for most of the night, it is still too low for imaging, reaching a maximum altitude of 14 degrees.

Haumea: in Bootes, mag 17.4
On 1st it is briefly high enough for imaging from 23.00 to 23.45, when it will be at 27 degrees in the west, setting at 02.23.  By 31st it is only at a reasonable altitude for a few minutes around 21.30, setting at 00.24.

Makemake:  in Coma Berenices, mag 17.3
Very low this month.  On 1st it is at 22 degrees in the west as the sky darkens, setting at 02.03.   By 31st it is down to 19 degrees in darkness, setting soon after midnight.

Eris: in Cetus, mag 18.8
The cause of poor Pluto's demotion, appropriately named after the goddess of discord, is higher but very much fainter and therefore only a target for the most experienced astrophotographers using the very best equipment.  On 1st it rises at 00.20 and reaches 24 degrees in the SE by dawn. On 31st it rises at 22.18 and culminates, 35 degrees in the south, at 04.18, only a few minutes after the end of astro darkness.

Comets

C/2020 F3 (NEOWISE) in Coma Berenices, mag 5.5  (maybe!)
Moving away from the Sun and fading rapidly, also very low in the evening sky - though, for a change this one did live up to expectations.  On 1st it is best seen for a few minutes after 23.00, when it is 22 degrees above the western horizon. It moves into Virgo on 10th, when it is only 17 degrees in the west at dusk, setting at 00.46.  It is in Bootes on 12th to 15th, then back into Virgo on 16th.  On 31st it is only 8 degrees above the horizon as the sky darkens, setting at 22.43.  Predicted mag now 10.3, but remember the advice given in in-the-sky.org - take all magnitude forecasts with a pinch of salt, as comets are very unpredictable.

C/2019 U6 (Lemmon)  in Coma Berenices, mag around 8
This one, discovered by the Mount Lemmon Sky Survey in Arizona last October, was originally thought to be an asteroid. It was confirmed as a comet in March 2020.  Unlike the other 2 comets in the area, its position improves during August as it moves north eastwards.  On 1st it is almost midway between Haumea and Makemeke, and only about 2 degrees from C/2017 T2 (PanSTARRS) .  It will be 21 degrees above the horizon at dusk, setting at 01.42. It moves into Bootes on 3rd, when it is at 23 degrees at 23.00, setting at 01.47.  By mid month it gets to 30 degrees and should be high enough for imaging for about an hour from 22.15, still setting around 2am.  By 31st it will have moved to about 6 degrees NW of Haumea and have faded to mag 10.  It will then be at 36 degrees in the west as the sky darkens around 21.30 and be reasonably high until just after 23.00, setting at 02.02.

C/2017 T2 (PanSTARRS) in Coma Berenices, mag 9.9
High enough for imaging in the first few days of the month.  On 1st it is 23 degrees above the western horizon around 11pm, setting just before 2am.  From then on, as Lemmon gets higher, this one gets lower. It moves into Bootes on 6th but is down to 21 degrees at dusk, setting at 01.26.  It is in Virgo from 24th, probably now around mag 10.5 and only 15 degrees in the west as the sky darkens.  On 31st, predicted mag 10.7, it's even lower, only 13 degrees, and sets at 23.06.

For more information, including position charts and exact co-ordinates of any Solar System object, see


For news about comets
www.cometwatch.co.uk   This has now been updated.

Meteor Showers

One really major shower this month.

Perseids, active July 17th to August 26th, peak on the 12th, between 14.00 and 17.00.  ZHR figure varies according to source used - somewhere between 50 and 150 from a dark sky site.  The radiant is circumpolar from Manchester, at its highest at 07.00, so the best time for viewing is just before dawn on 12th. It might also be worth looking after dusk on that day.  These are fast moving meteors, often leaving bright trails.  The third quarter Moon may interfere, rising at 23.41 on 11th and 00.03 on the morning of 13th. This shower occurs when the Earth passes through debris left in the wake of Comet 109P/Swift-Tuttle

There are also 2 very minor showers#

Kappa Cygnids:  active August 3rd to 25th.  This shower is said to be unpredictable as the dust cloud responsible is very diffuse.  The peak is given as 17th but could be as early as 12th or 14th, with a shorter period of activity.  ZHR 5, at best.  The radiant is circumpolar, highest at 22.00, so they are best seen as the sky darkens. The uncertainty of the timing of the paek of this shower means that it probably isn't worth going out especially to look for meteors but, if you happen to be observing on one of the possible peak evenings,you might just see one or two.  If there is a peak on 12th, they should be easily distinguishable from Perseids, as well as coming from a different direction, the Kappa Cygnids are much slower moving.  The parent body is not known for sure but could be minor planet 2008 ED9.

Aurigids:  August 28th to Sept 5th, peak August 31st, ZHR 6  The circumpolar radiant is highest at 09.00, so the best time to look is just before dawn on 31st. On the night of 30th/31st the 95% Moon rises at 19.30 and sets at 03.39 - less than half an hour before the end of astro darkness.  Parent comet for these is C/1911 Kiess.


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