The night sky in July 2020

posted 29 Jun 2020, 14:56 by Pete Collins   [ updated 30 Jun 2020, 09:47 ]
by Anne Holt

Sunrise      1st:   04.44       31st:   05.23
Sunset       1st:   21.40       31st:   21.05

Astronomical darkness
1st:  none       31st:  00.43  to  01.47
None until the morning of 30th, when we have 32 minutes.

Day  length     1st:  16.55.35       31st:  15.42.11

Earth is at aphelion on 4th at 12.34, when it will be 1.02 AU from the Sun.

Full Moon:  5th at 05.44      New Moon:  20th at 18.32

Lunar apogee:   12th at 20.28   (404,200km)
Lunar perigee:   25th at 05.55   (368,366km)

The July full Moon is known as the Buck Moon, because this is the time that male deer start to grow new antlers.  Other names are the Thunder Moon, the Old English / Anglo Saxon Hay Moon and the medieval English Mead Moon. The Chinese name is the Hungry Ghost Moon, because of the Hungry Ghost Festival which was held at this time - when the veil between this world and the next was said to be thin, so spirits could move freely between the two.

Highlights

At last we have the return of astro darkness, but only right at the end of the month.  On 5th there's another penumbral lunar eclipse, this time as the Moon is setting so, with a very clear sky and a low SW horizon, it might be possible to see a slight darkening at the top of the Moon's disc in the half hour before it sets at 04.42. 
Jupiter and Saturn both reach opposition this month, low in the southern sky, with Jupiter much brighter.  However Saturn's rings are at their best at this time. Mars is improving in both brightness and position, from mid month it is in the northern celestial hemisphere. Venus is also getting higher in the pre-dawn sky. 
There are a couple of minor meteor showers at the end of the month but both are better seen from further south.  However we could have some fireballs and there may be an outburst of the (usually almost non existent) July Draconids.  Once again we have a comet which may (or may not) be a naked eye object when it gets high enough in our Manchester sky to be visible. Unfortunately it fades rapidly as it gets higher in the sky.
And we still have the chance of seeing some noctilucent clouds. There have already been some good displays this year; they have been seen in Oregon, USA, which is about 10 degrees further south than Manchester. 

Planets

Mercury:  in Gemini, mag 5.7
Not visible until late July, and even then it remains very low.  On 1st it is at inferior conjunction and is only 4 degrees 26' from the Sun.  The 2% Moon passes close to the planet around sunrise on 19th but Mercury will be on the horizon as the sky brightens so is unlikely to be seen.  On 22nd it reaches greatest western elongation at 20 degrees separation from the Sun but, because of the shallow angle of the ecliptic, is still very low rising at 03.40 and only 3 degrees above the horizon at dawn.  It will, however, be much brighter at mag 0.3.  On 31st, now at mag -0.8, it rises at 03.47 and gets to 6 degrees before the sky is too bright for it to be seen.

Venus:  in Taurus, mag -4.5
Improving its position in the morning sky and, because it is so much brighter, much easier to see than Mercury even when very low.  On 1st it rises at 03.05  and reaches 8 degrees by dawn.  From 6th it passes through the V shaped Hyades cluster and on 8th is at its greatest brightness, only marginally brighter than at the start of the month.  On this day it rises at 03.05 and should be easily visible an hour later, as the sky begins to brighten. It is at aphelion (furthest from the Sun) on 10th, when its distance is 0.73 AU.  However, because its orbit is almost circular, there is very little difference between its nearest and furthest points.  On 11th it passes about 1 degree north of Aldebaran, 'the eye of the bull'.  Venus can't get quite as far south as the bright star - yet! On August 27th, in the year 5336 there will be an occultation. No idea whether this will be visible from Manchester - or even whether there will still be a Manchester at this time. On 17th the waning crescent Moon passes north of the planet, closest - 3 degrees 03' - at 07.06.  On 31st it rises at 02.06 slightly fainter at mag -4.4 and reaches 22 degrees by dawn.

Mars:  in Pisces, mag -0.5
Gets higher and brighter during the month.  On 1st it rises at 00.50 and is easily visible from around 2am until dawn, when it is at 24 degrees in the SE. It moves into Cetus on 9th and on the night of 11th/12th the gibbous Moon passes 1 degree 46' to the south, while they are still below the horizon.  They will be separated by 3 degrees 30' at 4am, when Mars will have reached 30 degrees in the SE.  Also around this time it crosses the celestial equator as it continues its northward journey.  On 17th it goes back into Pisces; it doesn't actually change direction at this time, it's just how the constellation borders lie. On this day it rises at 23.29  and is visible from 00.30, reaching 37 degrees in the south by dawn. By 31st it will be at mag -1.1, rising at 23.17 and reaching 38 degrees before the sky begins to brighten shortly before 05.00.

Jupiter:  in Sagittarius, mag -2.7
On 1st it rises at 22.15, reaching 8 degrees in the SE before midnight and culminating, 6 degrees higher, in the south at 02.14. On 5th, the just past full Moon passes 1 degree 05' south of the planet at 22.36.  They should be visible about an hour later when Jupiter is 7 degrees above the SE horizon. Highest point, 14 degrees, at 01.56 on 6th when the separation will be 3 degrees. It is at opposition, when it is directly opposite the Sun in the sky, on 14th.  On this day it rises at 21.16 and culminates at 01.16. It is at its brightest on the night of 16th/17th but, as it is only around 0.02 of a magnitude higher than on 1st, no one will notice. On 31st it rises at 20.06 and culminates just before midnight, still at only 14 degrees in the south.

Saturn:  in Capricorn, mag 0.2
Slightly higher but much fainter than the nearby Jupiter.  On 1st it rises at 22.31 and reaches 10 degrees in the SE by 02.39.  It joins Jupiter in Sagittarius on 4th and on 6th is also visited by the Moon, which is 6 degrees SW of Saturn at 2am, closest, 2 degrees 27' in daylight at 10.13.  It is at opposition on 20th, when it rises at 21.13 and reaches 15 degrees in the south at 01.19. The planet's northern hemisphere is currently tilted towards us, the rings are at an angle of 21 degrees and are a spectacular sight when seen through a telescope. Around opposition, when sunlight falls directly on to the planet from our point of view,the rings are noticeably brighter. This is because the shadows of the particles comprising them fall directly behind,  so they can't be seen and there isn't the usual dimming - more sunlight is reflected back towards us. This is known as the Opposition Surge, or Seeliger Effect after Hugo von Seeliger who, in 1887, first explained this and saw it as proof that the rings were not solid structures but were made up of lots (now thought to be billions) of individual particles.  On 31st Saturn rises at 10.38, reaches 10 degrees in the SE by 22.15 and culminates, 5 degrees higher, at 00.32.

Uranus:  in Aries, mag 5.8
A  morning object, not visible in early July.  On 1st it rises at 01.35 and is on the horizon at dawn. Its position improves during the month, on 14th it rises at 00.45 and reaches 13 degrees in the east as the sky brightens.  A week later it rises at 00.18 and is at 21 degrees by daybreak.  On 31st it rises at 23.35 and should be high enough to be seen soon after 2am, reaching an altitude of 31 degrees in reasonable darkness.  As always, excellent eyesight and a very dark sky site are necessary in order to see it with the naked eye.  For the rest of us binoculars are needed, or a scope to show the small blue/green disc.

Neptune:  in Aquarius, mag 7.9
Another one which isn't easy to see at the start of July. On 1st it rises at 00.20 and is only 11 degrees above the horizon by dawn. On 10th, at 03.00, the Moon passes 7 degrees SW of the planet, which will be 19 degrees above the horizon as the sky brightens.  From mid month it should be high enough in the still dark sky for telescopic observation. On 13th it rises at 23.29 and reaches 22 degrees in the SE before the sky begins to brighten.  On 31st it rises at 22.10 and almost reaches its highest point, 31 degrees, in the south in darkness.  A reasonable sized amateur scope should show the planet's disc, much bluer than Uranus, thought to be because the atmosphere has a higher concentration of methane, which absorbs light at the red end of the spectrum and reflects the blue.

Dwarf Planets

Ceres:  in Aquarius, mag 8.6
The only one of the 5 which orbits in the (relatively) nearby asteroid belt, is very low this month.  On 1st it rises at 01.24 and on 31st at 23.29.  By this time it will have brightened to mag 8.1 but still be too low for telescopic observation.

The rest are very faint, distant and, because they take so long to orbit the Sun, move very slowly against the background stars. Their orbits are highly inclined to the plane of the solar system, so they are not necessarily found close to the ecliptic.  With the exception of Pluto, found in Feb 1930, their discovery was announced in a short period between late Dec 2004 and late May 2005. Of these 3, only Haumea is now in a different constellation, having crossed the border between Coma Berenices and Bootes in 2007.

Pluto: in Sagittarius, mag 14.9.
Much too low for observing or imaging, as it will be for many years yet.  it is at opposition on 16th, less than 1 degree south of Jupiter.

Haumea: in Bootes, mag 17.4, and Makemake in Coma Beenices, mag 17.1, are even further and fainter than Pluto but better bets for imaging as they are higher in the sky.  Haumea reaches 32 degrees in the west on 1st and 27 degrees on 31st.  Makemake is slightly lower at 2 degrees and 23 degrees respectively.

Eris: in Cetus, mag 18.5
Faintest and furthest of the 5 officially designated dwarf planets.  It is high enough for imaging by serious, experienced astrophotographers at the end of July. On 1st it rises at 00.24 and reaches 23 degrees in the east at 3am, a short time before the sky brightens.
Eris takes 558 years to orbit the Sun, but that's nothing compared to some distant objects.  Sedna, with a very eccentric orbit taking it from the outer reaches of the Kuiper Belt to the inner part of the, as yet hypothetical, Oort Cloud  has a period of around 11,000 years.  It's one of the bodies thought to be influenced by some distant, massive object, maybe planet 9.

A couple of asteroids are at opposition in July.

532 Herculina, in Sagittarius, mag 9.5
Reaches opposition on 3rd, when it culminates at 01.12, but is only 16 degrees above the horizon.

2 Pallas, in Sagitta, mag 9.6.
The second asteroid belt body to be discovered, and the third biggest, having 7% of the mass of the entire belt, is at opposition on 15th, when it is at 57 degrees in the south at 00.41. This has a similar magnitude to Herculina but should be much easier to observe, being so much higher - again, because of the inclination of its orbit.

Comets

C/2020 F3 (NEOWISE) in Taurus, mag -0.3 (or less)
This was discovered on March 27th, when it was at mag 17. It was at one time predicted to reach -2.6 in early July, but now the highest estimate is -0.3.  other sources give it as mag 2 or 3, or maybe as low as 6.  All agree that it will fade rapidly during the month.
On 1st it rises at 02.32 but only reaches 3 degrees above the horizon by dawn. it is at perihelion on 3rd, when it moves into Auriga, rising at 02.55 and getting to 7 degrees in darkness.  It get higher in the morning sky but fades rapidly.  It becomes circumpolar on 8th when it will be at 14 degrees in the east as the sky begins to brighten. It moves into Lynx on 13th, when it should be visible fom around 22.30 to 04.00, reaching 15 degrees in the NE by dawn but down to mag 1.8 (or less). Crosses into Ursa Major on 18th, when it is at 19 degrees in the NW at 23.00, down to 13 degrees at 03.30. It ends the month in Coma Berenices, and should be visible, 22 degrees above the western horizon, for a short time after 23.00, much fainter now - highest estimate 5.5.
The home page of www.cometwatch.co.uk  has been updated to show images and a finder chart for this one.

C/2019 U6 (Lemmon) in Sextans, mag 5.5
Not visible from here until the latter part of July. It is moving  north eastwards but dimming as it gets higher. It passes through Leo and Virgo, still below our horizon at dusk,  and into Coma Berenices on 23rd, whe it will be at 13 degrees in darkness but fainter at a probable mag of around 7.1.  On 31st it is at 21 degrees in the west at dusk, setting at 01.39, predicted mag now 7.9.

C/2017 T2 (PANSTARRS) in Canes Venatici mag 9.3
Moving south westwards and fading, circumpolar for the first week in July, on 1st it is at 35 degrees in the west soon after midnight, down to 26 degrees in the NW at o 01.45. On 9th it sets for a short while and is at its highest, 32 degrees in the west, around midnight.  It is in Coma Berenices from 15th, when it will be at mag 9.5 and best seen for about an hour after midnight when it reaches 30 degrees in the west.  On 31st it is down to 24 degrees, best seen soon after 11pm, setting at 02.04, slightly fainter, predicted mag 9.9.

Websites used

www.cometwatch.co.uk has only updated its home page to give information on C/2020 F3 (NEOWISE).  The rest has not been changed since April, or even earlier.

Meteor Showers

A couple of minor showers at the end of the month, both favouring observers further south.

Southern Delta Aquarids, active July 12th to August 23rd, peak on the night of 28th/29th (or maybe 30th - sources fail to agree, yet again)  ZHR 25, but the radiant is very low as seen from Manchester, so expect far fewer.  These are faint, medium speed meteors with no trails and no fireballs.  Parent comet 96P/Machholz.

Alpha Capricornids, active July 3rd to August 15th, they have a plateau-like peak centred on 29th.  ZHR 5 but again fewer from our latitude.   Slow moving meteors but worth looking out for as as this shower often includes fireballs.  Parent comet 169P/NEAT.

There could be an outburst of the July Draconids on July 28th, around 01.30.  This shower usually shows very little activity, but the last time that Earth was in the same position realtive to the dust cloud, in 2016, a ZHR of aroud 100 was recorded.  The parent comet is unknown, probably one of the Jupiter family - comets which have had their orbits altered by a close encounter with the gas giant and now have a period of less than 20 years.

The radiant of the antihelion source moves through Capricorn into SW Aquarius during July.  The Capricornids have a radiant close by but should be easily distinguishable as meteors from the ANT are much faster moving.






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