At first, the Sun lies within the constellation of Gemini, until the early morning on the 21st, when it crosses the border into neighbouring Cancer.
A significant date, this month is that of the Earth’s Aphelion - July 4th, when at 22h11, the Earth is at the furthest distance our planet can be from the Sun, 152 104 278 km (1.0167543 au) (centre to centre); ‘au’
is the symbol for an astronomical unit; the mean (average) distance between the Earth and the Sun.
As in June, twilight persists all night, and the season for observing Noctilucent Clouds continues. Look towards
the northern sky during the two hours centred on astronomical midnight for these ethereal silvery veils in the northern sky.
Moon is at Apogee,
its furthest point from the Earth, on the 21st July at about 00h00. The angular diameter of the Moon is 30’ of arc. Perigee, when the Moon is at its nearest to Earth, is on the 5th at 05h. The angular diameter then
is 33' of arc.
New Moon in July is on the 2nd at 19h17, when the Moon passes to the south of the Sun, in the constellation of Gemini. There is a total solar eclipse visible in most of
South America except the extreme NW. Totality can also be seen from the southern Pacific Ocean.
First Quarter is on the 9th, at 10h55, when the Moon is in the constellation of Virgo to
the NW of Spica (alpha Virginis), the brightest star in Virgo.
Full Moon is on the 16th at 21h39 in the constellation of Sagittarius, 8° east of Saturn. There is a partial eclipse
of the Moon at this time, in which the northern 60% of the Moon’s surface is immersed in the Earth’s umbral shadow. From Scarborough in the UK, the umbral phase of the eclipse starts just after moonrise, and most of the eclipse can be seen from
here. The event will be quite spectacular for a partial eclipse This is because of the low altitude of the Moon above the horizon. In consequence, it appears slightly larger than normal due to our brain’s Moon illusion - giving rise to this erroneous
idea of a ‘supermoon’. During the eclipse, observers should take a look at nearby Saturn, which has just past its Opposition (on the 9th), and is at its closest to the Earth.
Quarter Moon, on the Aries/ Cetus border is on the 25th, at 01h19.
Look for Earthshine on the dark hemisphere of the waxing Moon from the 4th to the 8th and on the
waning Moon at the very end of the month.
Mercury may be visble during the first few days of July, low down in the NW sky
in bright evening twilight within 5° of the horizon. You will need binoculars to glimpse this elusive object at around 21h U.T. Mars lies some 4° to the right of Mercury, but at visual magnitude +1.8 will be difficult to see, more so than the brighter
Mercury at magnitude +1.0 (almost two and a half times brighter than Mars.
Venus is an exceedingly difficult object to see now, as it is disappearing in the bright morning twilight. The planet is
approaching Superior Conjunction with the Sun, which takes place in the middle of August. The planet rises approximately 30 minutes before the Sun, so it can be dangerous to spend time scanning the horizon in order to see it with binoculars, for fear of inadvertently
catching the blinding rays of the Sun as it rises. It is not advisable to do this therefore.
Mars sets within 30 minutes of the Sun for most of the month, and will not be visible.
Jupiter in the constellation of Ophiuchus is a most brilliant object in the sky of summer, and can be seen until the early hours of the morning. By the end of July it sets at midnight. It rises in the SE, culminates
in the south at an altitude of 13°, and sets in the SW. Jupiter is in Conjunction with the Moon overnight on the 13th to the 14th. At midnight they are 1.5° apart, Jupiter lying to the SW (lower right) of the waxing gibbous Moon.
Remember to look at the 'nightly dance' of the Jovian satellites through well-focussed and firmly fixed binoculars. On the front page of these Sky Notes, the daily configuration of the four Galilean satellites is shown for late evening.
Saturn, despite its low altitude in Sagittarius, is in Opposition (nearest to the Earth) on the 9th, and culminates on the south meridian at an altitude of 14° at midnight. The Moon may be seen approaching
Saturn on the morning of the 16th, when at 02h00 on this morning, Saturn lies 3° to the NE (upper left) of the Full Moon. An occultation of Saturn takes place at 07h00, but the Moon has set by this time and this event is only visible from most
of central South America (except eastern Brazil), and the southern Pacific Ocean. There is a close appulse between the two, for observers in North Island, New Zealand, and a grazing occultation at the most northerly tip of that island. A small telescope will
show admirably the northern surface of the rings which are well presented towards the Earth. Magnitude +8 satellite Titan may be seen to the east of Saturn on the 3rd and the 19th, and at its western elongation on the 11th
and 27th. Both the planet’s rings and Titan can be seen through a small telescope.
Uranus in Aries is visible from around midnight until twilight interferes during the short nights
of July. Its position may be seen on the Remote Planets page of these Sky Notes.
Neptune in Aquarius may be seen when evening twilight fades until morning twilight begins. Its position is seen on
the Remote Planet page.
Pluto is at opposition on the 14th in the constellation of Sagittarius. Its magnitude is +14.27, and the planet culminates at midnight at an altitude of 14°.
An astronomical telescope is required to spot this remote little world, visited last year by the New Horizons space probe. With a dark sky at astronomical midnight, it is possible to image this outpost of the Solar System. Pluto’s position in relation
to the faint stars in this area of Sagittarius may be found on the Remote Planes page.
Two minor meteor showers take place at the end of the month. One is the alpha Capricornids, maximum July 30th
– the zenithal hourly rate is 5, and the conditions this year should be favourable. Many Capricornids are slow moving and colourful if you want to stay up and spot some of them.
On the 31st, we have the maximum
of the southern delta Aquarids, with up to 20 an hour, and although these meteors tend to be faint, conditions are favourable.
Towards the end of July, the Perseid Meteor Shower begins, and continues
towards its maximum on August 13th at 07h.
Constellations visible in the south around midnight, mid-month, are as follows: Sagittarius, Sagitta, Aquila, Lyra and Cygnus. The latter constellations contain
Patrick Moore’s ‘Summer Triangle’, consisting of the three bright stars, Altair in Aquila, Vega in Lyra, and Deneb in Cygnus. Cygnus is sometimes called the ‘northern cross’ because of the cruciform shape of its five main stars.
All times are GMT 1° is one finger width at arm’s length.
The phenomena of the month : July 2019
Times are given in UT for SCARBOROUGH (0° 25' 0" W, 54° 16' 3" N, zone Z).
Date Hour Description of the phenomenon
yyyy mm dd hh:mm
2019 07 02 02:20 Opposition of the asteroid 18 Melpomene with the Sun (dist. to the Sun = 2.263 AU; magn. =
2019 07 02 19:16 NEW MOON (total eclipse of the Sun not visible in SCARBOROUGH)
2019 07 02 21:38 Maximum of the variable star delta Cephei
2019 07 03 05:43 Minimum of the variable star Algol (beta Persei)
2019 07 04 23:00 The Earth at its aphelion (distance to the Sun = 1.01675 AU)
2019 07 05 00:48 Maximum
of the variable star eta Aquilae
2019 07 05 04:54 Moon at perigee (geocentric dist. = 363726 km)
2019 07 05 10:43 Minimum of the variable star beta Lyrae
2019 07 06 02:31 Minimum of the variable star Algol (beta Persei)
2019 07 07 07:00 Mercury at its aphelion (distance to the Sun = 0.46670 AU)
07 08 06:26 Maximum of the variable star delta Cephei
2019 07 08 17:46 Close encounter between Mercury and Mars (topocentric dist. centre to centre = 4.0°)
2019 07 08
23:20 Minimum of the variable star Algol (beta Persei)
2019 07 09 10:55 FIRST QUARTER OF THE MOON
2019 07 09 17:08 OPPOSITION of Saturn with the Sun
2019 07 10 21:27 Maximum of the variable star zeta Gemini
2019 07 11 20:09 Minimum of the variable star Algol (beta Persei)
2019 07 12 05:02 Maximum of the variable
star eta Aquilae
2019 07 13 15:13 Maximum of the variable star delta Cephei
2019 07 13 16:18 Close encounter between Mars and M 44 (topocentric dist. centre to centre = 0.4°)
2019 07 14 14:49 OPPOSITION of Pluto with the Sun
2019 07 14 16:57 Minimum of the variable star Algol (beta Persei)
2019 07 16 21:38 FULL
MOON (partial eclipse of the Moon partly visible in SCARBOROUGH)
2019 07 17 13:46 Minimum of the variable star Algol (beta Persei)
2019 07 18 09:17 Minimum of the variable
star beta Lyrae
2019 07 18 23:59 Maximum of the variable star delta Cephei
2019 07 19 09:16 Maximum of the variable star eta Aquilae
07 20 10:34 Minimum of the variable star Algol (beta Persei)
2019 07 21 00:01 Moon at apogee (geocentric dist. = 405480 km)
2019 07 21 01:03 Maximum of the variable star
2019 07 21 12:34 INFERIOR CONJUNCTION of Mercury with the Sun (geoc. dist. centre to centre = 5.0°)
2019 07 23 07:23 Minimum of the variable star Algol (beta
2019 07 24 08:47 Maximum of the variable star delta Cephei
2019 07 25 01:18 LAST QUARTER OF THE MOON
2019 07 26 04:12 Minimum
of the variable star Algol (beta Persei)
2019 07 26 13:30 Maximum of the variable star eta Aquilae
2019 07 28 10:08 Meteor shower : Piscis Austrinids (5 meteors/hour at zenith;
duration = 26.0 days)
2019 07 29 01:00 Minimum of the variable star Algol (beta Persei)
2019 07 29 17:34 Maximum of the variable star delta Cephei
2019 07 30 12:18 Meteor shower : Alpha Capricornids (5 meteors/hour at zenith; duration = 43.0 days)
2019 07 30 12:18 Meteor shower : S. Delta Aquarids (25 meteors/hour at zenith; duration = 43.0 days)
2019 07 31 04:38 Maximum of the variable star zeta Gemini
2019 07 31 07:52 Minimum of the variable star beta Lyrae
2019 07 31 21:49 Minimum
of the variable star Algol (beta Persei)
Generated using COELIX software