AUGUST 2018

 

As the month begins, the Sun is passing through the stars of Cancer, until around 00h on the 11th, when it crosses the boundary into Leo, where it remains for the rest of the month. From the beginning of the month, truly dark nights begin again in northern UK.

 

 

 

The Moon

 

 

 

The Moon is at perigee, its nearest to the Earth, at 18h on the 10^th (33.1 minutes of arc diameter). It is at apogee (furthest from the Earth) at 11h25 on the 23^rd (29.5 minutes of arc)

 

 

 

Last Quarter Moon is on the 4^th at 18h19 on the Cetus/Aries border.  

 

 

 

New Moon is on the 11^th at 09h58  on the Cancer/Leo border, when it passes about 1° above the Sun. A partial eclipse may be seen by observers in the NW Territories of Canada, SE and E China and the extreme eastern portion of Siberia. In Canada the eclipse is in the early morning; in China and Asia, just before sunset on the 11^th.

 

 

 

First Quarter Moon at 07h49 on the 18^th takes place in the constellation of Libra.

 

 

 

Full Moon occurs at 11h57 on the 26^th in the constellation of Aquarius. Some would consider this to be the Harvest Moon, as it corresponds more closely to at the time of the grain harvest in the northern hemisphere; however this title is given to the September Full Moon which will be described next month.

 

 

 

It may be possible to glimpse Earthshine on the night hemisphere of the waxing crescent Moon from the 12^th  to the 17^th and on the waning crescent Moon from the 5^th to the 10^th.

 

 

 

 

 

The Planets

 

Mercury is at inferior conjunction with the Sun on the 9^th. Thereafter, it becomes a morning object and achieves a good morning apparition during the second half of August. The planet reaches its greatest western (18°) elongation from the Sun on the 26^th, when it rises two hours before the Sun. Use binoculars and scan the eastern horizon at around 04h, and you should be able to see the bright planet in the increasing dawn twilight, close to the horizon.

 

 

 

Although Venus (in Virgo) reaches its greatest elongation east (46°) of the Sun on the 17^th, the planet is only visible for an hour after sunset before Venus itself sets. This is due to the very low altitude of the planet, because it lies south of the ecliptic, and the fact that the ecliptic in that direction lies at a very shallow angle to the horizon. Look towards the WSW at around 20h on the 14^th, and you will see a lovely conjunction of the waxing crescent Moon with Venus. At this time Venus lies 4.7° below the Moon, and is, in consequence, nearer the horizon. If you look at Venus through a small astronomical telescope at this time, you will see that the planet is at dichotomy, i.e. the planet exhibits a phase similar to that of a ‘half-moon’, minus the maria and craters of course. Notice also that Venus is far brighter than the Moon, because of the highly reflective nature of the clouds in its atmosphere.

 

 

 

Mars was in Opposition at the end of July and so continues to be visible for most of the night, shining with its unmistakeable ochre-coloured light. Mars remains bright throughout the entire month and lies on the Capricornus/Sagittarius border. For northern observers, the planet remains low in the southern sky, culminating (ie crossing the southern meridian) at an altitude of around 10° at 23h mid-month. Through a decent small astronomical telescope it is possible to identify some of the dark albedo features such as Syrtis Major and also the ‘shrinking’ South Polar Ice Cap and the haze surrounding it.

 

The magnitude of Mars during August fades slightly from -2.6 to -2.2 as the Earth-Mars distance begins to increase once again. However, it is the brightest star-like object in the late evening sky after Venus and Jupiter have set. The waxing gibbous Moon and Mars are in conjunction on the evening of the 23^rd. When they cross the south meridian at 22h, Mars lies 6° below the Moon.

 

 

 

At the beginning of August, Jupiter sets just before 22h30, but by the end of the month the planet sets just 2hours after the Sun, so the period of visibility is decreasing in the evening sky.

 

The giant planet remains in the constellation of Libra, next to the binocular double star Zubenelgenubi (alpha Librae). The broad waxing crescent Moon may be seen approaching Jupiter on the evening of the 16^th, and on the 17^th the two are in conjunction. Look for them low in the SW sky on the 17^th, when the two are separated by an angle of 5°. The Moon at this time is almost at its First Quarter phase. Continue to observe the ever-changing positions of the Galilean moons through well focussed and firmly fixed binoculars.

 

 

 

Saturn, at magnitude +0.3, becomes visible low in the southern sky as soon as daylight fades. Mid-month the planet culminates in the south, just before 21h, at an altitude of about 14°. Saturn is about as far south on the celestial sphere as it can possibly be, in the constellation of Sagittarius. The northern surface of the rings is still well presented towards the Earth, and so should delight observers with small telescopes on glimpsing this gem of the Solar System. Brighter Mars lies 30° to the east of Saturn and Jupiter almost 50° to the west. The waxing gibbous Moon lies 6° to the west of Saturn on the 20^th and 5° to the east of Saturn on the 21^st. Saturn’s largest moon Titan is a telescopic object and may be seen at its greatest elongation east of the planet on the 2^nd and 18^th, and is at greatest western elongation on the 10^th and 26^th. Throughout August Saturn sets around astronomical midnight, 00h.

 

 

 

Uranus in the southern reaches of the constellation of Aries rises mid-evening during August. It lies on the threshold of naked eye visibility, but is readily visible in binoculars if you know where to look for it. There is a location chart available

 

on the ‘Remote Planets’ page, which may be accessed using the MENU of these Sky Notes. The planet lies at the same Right Ascension as Measarthim (gamma Arietis), the celebrated ‘cat’s eyes’ double star, some 8° below the star.

 

 

 

 

 

Neptune, three times fainter than Uranus, lies in the constellation of Aquarius. It culminates in the South at an altitude of 30° around 01h, the same time as the first magnitude star Fomalhaut (alpha Piscis Austrini) in the constellation of the ‘southern fish’. Fomalhaut is the lowest altitude first magnitude star visible from the UK.

 

Greater details of the planet’s position are to be found on the ‘Remote Planets’ page, accessible via the MENU.

 

 

 

 

 

One of the best shooting star showers of the year peaks at 01h on the 13^th,  and so is best seen during the early hours of the morning of that day. These meteors are called the Perseids, or the ‘Tears of St Lawrence’. Expect to see 80 or more shooting stars each hour, and especially in the hour or so before dawn. Seeing conditions are very favourable this year because the moon is absent from the sky. This is a rich shower of fast meteors, some of which will leave persistent trails. The Perseid meteors are associated with the Swift-Tuttle comet discovered in the nineteenth century. The period of this comet is 133 years and its next close approach to the earth will take place on August 5^th 2126. The current predicted distance between the comet and the earth on that occasion is 22,900,000 km (14,200,000 miles). Expect an exceptional shower in August of that year!!

 

There is more information on a dedicated page accessed via the MENU. This shower is active from July 23 to August 20.

 

 

 

Constellations visible in the south around midnight, mid-month, are as follows: Capricornus, Aquarius, Equuleus (the Little Horse), Delphinus (The Dolphin) and Cygnus. The Milky Way is at the zenith, and spans the sky from the NE to the SW.

 

 

 

All times are GMT     1° is one finger width at arm’s length.

 

 

 

 

 

 

 

 AUGUST EVENTS SUMMARY (Using Coelix Software)

The phenomena of the month : August 2018
Times are given in standard time for SCARBOROUGH (0° 25' 5" W, 54° 16' 30" N, zone UT).

Date Hour Description of the phenomenon
yyyy mm dd hh:mm

 

2018 08 01 17:32 Maximum of the variable star eta Aquilae
2018 08 01 18:15 Minimum of the variable star Algol (beta Persei)
2018 08 02 20:20 Simultaneous transits on Jupiter: one satellite and shadows of two satellites.
2018 08 02 23:46 Minimum of the variable star beta Lyrae
2018 08 04 00:41 Close encounter between the Moon and Uranus (topocentric dist. centre to centre = 5.6°)
2018 08 04 04:36 Maximum of the variable star delta Cephei
2018 08 04 15:04 Minimum of the variable star Algol (beta Persei)
2018 08 04 18:18 LAST QUARTER OF THE MOON
2018 08 07 11:53 Minimum of the variable star Algol (beta Persei)
2018 08 08 21:47 Maximum of the variable star eta Aquilae
2018 08 09 02:06 INFERIOR CONJUNCTION of Mercury with the Sun (geoc. dist. centre to centre = 4.8°)
2018 08 09 13:23 Maximum of the variable star delta Cephei
2018 08 09 20:58 Simultaneous transits on Jupiter: two satellites.
2018 08 09 22:48 Maximum of the variable star zeta Gemini
2018 08 10 04:22 Comet C/2016 M1 PANSTARRS at its perihelion (dist. to the Sun = 2.211 AU; magn. = 9.7)
2018 08 10 08:41 Minimum of the variable star Algol (beta Persei)
2018 08 10 18:05 Moon at perigee (geocentric dist. = 358078 km)
2018 08 11 09:58 NEW MOON (partial eclipse of the Sun not visible in SCARBOROUGH)
2018 08 12 21:54 Meteor shower : Perseids (110 meteors/hour at zenith; duration = 38.0 days)
2018 08 13 05:30 Minimum of the variable star Algol (beta Persei)
2018 08 14 22:10 Maximum of the variable star delta Cephei
2018 08 15 21:59 Comet C/2017 S3 PANSTARRS at its perihelion (dist. to the Sun = 0.208 AU; magn. = 4.1)
2018 08 15 22:21 Minimum of the variable star beta Lyrae
2018 08 16 02:01 Maximum of the variable star eta Aquilae
2018 08 16 02:18 Minimum of the variable star Algol (beta Persei)
2018 08 17 06:00 GREATEST EASTERN ELONGATION of Venus (45.9°)
2018 08 18 01:08 Meteor shower : Kappa Cygnids (3 meteors/hour at zenith; duration = 22.0 days)
2018 08 18 07:48 FIRST QUARTER OF THE MOON
2018 08 18 20:32 End of occultation of 49 Lib (magn. = 5.47)
2018 08 18 23:07 Minimum of the variable star Algol (beta Persei)
2018 08 20 02:23 Maximum of the variable star zeta Gemini
2018 08 20 06:57 Maximum of the variable star delta Cephei
2018 08 21 19:55 Minimum of the variable star Algol (beta Persei)
2018 08 21 22:01 Close encounter between the Moon and M 22 (topocentric dist. centre to centre = 2.3°)
2018 08 23 06:16 Maximum of the variable star eta Aquilae
2018 08 23 11:23 Moon at apogee (geocentric dist. = 405746 km)
2018 08 24 16:44 Minimum of the variable star Algol (beta Persei)
2018 08 25 15:44 Maximum of the variable star delta Cephei
2018 08 26 11:56 FULL MOON
2018 08 26 12:23 Opposition of the asteroid 230 Athamantis with the Sun (dist. to the Sun = 2.278 AU; magn. = 10.2)
2018 08 27 00:00 GREATEST WESTERN ELONGATION of Mercury (18.3°)
2018 08 27 13:33 Minimum of the variable star Algol (beta Persei)
2018 08 28 20:56 Minimum of the variable star beta Lyrae
2018 08 30 04:31 Opposition of the asteroid 37 Fides with the Sun (dist. to the Sun = 2.590 AU; magn. = 10.5)
2018 08 30 05:58 Maximum of the variable star zeta Gemini
2018 08 30 10:21 Minimum of the variable star Algol (beta Persei)
2018 08 30 10:31 Maximum of the variable star eta Aquilae

2018 08 31 00:31 Maximum of the variable star delta Cephei