May 2019

At the beginning of the month the Sun continues its journey through the constellation of Aries, until the 14^th at around 19h00, when it crosses the astronomical border into Taurus. In the northern parts of the UK, twilight begins to persist all night, and there are no truly dark nights until the end of July. From now on, look out for Noctilucent Clouds, which are thought to be produced as a result of meteors passing through the upper atmosphere. These thin high clouds of ice crystals still catch the light of the sun, which even at midnight is not far below the northern horizon. Their appearance is that of silvery blue veils low in the northern sky, and may be seen an hour before and after midnight, often with interesting textures and patterns.

The Moon

The Moon is at perigee, the point of closest approach to Earth, at 22h00 on the 13^th, and apogee, the furthest distance away from Earth as it can be, takes place at 13h00 on the 26^th May.

New Moon is on the 4^th at 22h46. On this occasion, the Moon passes 6° south of the Sun on the Aries/Cetus border, passing 6° south of the Sun.

First Quarter at 01h13 on the 12th takes place in the constellation of Leo, 5° to the upper left of Regulus (alpha Leonis) in the western sky. 

The Full Moon of the flowering meadows (Anglo Saxon, Maed Monath) is on the 18^th at 21h12, when the Moon is in the eastern part of the constellation of Libra, just above the stars which represent the ‘head of the Scorpion’.

Last Quarter Moon is on the 26^th at 16h34 in Aquarius.

From the 5^th to the 10^th look for earthshine on the night hemisphere of the waxing crescent Moon. Look again for this phenomenon at the time on the waning crescent, during the first four and last three days of the month.

 Planets

You may be able to spot Mercury in the evening twilight at the very end of the month, when it sets 90 mins after the Sun. Binoculars will be a necessity because of the bright twilight. Search for the planet low in the NW sky at around 21h. Mercury should, at that time, be 5° above the horizon. (five finger widths at arm’s length.)

Venus rises at 04h00 on May 1^st. The planet is moving from the constellation of Pisces into Aries. It is increasing in northern declination, and so by the end of the month rises earlier at 03h00. Look for it in the ENE sky.

Mars moves from Taurus into Gemini and fades as the month progresses. On May 1^st, its visual magnitude is +1.64, which is slightly fainter than Castor (alpha Geminorum). The planet sets in the evening sky at around 23h00 throughout the month, and so the period of availability for observation decreases considerably as evening twilight increases. The angular diameter of Mars has now shrunk to 4 secs of arc, and there is little chance of seeing any detail on its surface through a small telescope. The thin waxing crescent Moon lies to the south of Mars on the 7^th between the horns of ‘The Bull’. The two are separated by 4°, and should be looked for in the NW on this evening; Mars lies to the north of the Moon.

Jupiter lies in the constellation of Ophiuchus at a low southerly declination. At the beginning May it rises at 23h00, and at 21h00 by the month’s end. With the exception of Venus, Jupiter is the brightest planetary object in the night sky at visual magnitude  (minus) -2.4. By the middle of the month the planet culminates at an angle of 14° in the south, as seen from Scarborough UK. The waning gibbous Moon may be seen some 4° to the east of Jupiter, as the two are rising, during the night of 20^th in the SE quadrant of the sky.

If you look through well focussed, firmly fixed binoculars, you will see the points of light, which are Jupiter’s Galilean satellites, slowly changing their positions on a nightly basis.

Saturn, like Jupiter, does not gain a high altitude when it crosses the southern meridian. It lies in the southern constellation of Sagittarius the Archer nearly 30° to the east of Jupiter. Saturn’s magnitude during month is +0.9, and so is a conspicuous object when it appears in the SE sky around 01h mid-month. On the 22^nd, the waning gibbous Moon lies between Jupiter and Saturn in the sky and the three will make a splendid trio low in the southern sky at around 02h. The rings of Saturn are inclined so that we have a good view of their northern surface. With a small telescope, try to spot Saturn’s brightest moon Titan (visual magnitude. +8), when it lies at western elongation on the 8^th and 9^th, and again on the 24^th and 25^th.Titan is at eastern elongation from Saturn on the 16^th. The waning gibbous Moon may be seen in close proximity to Saturn as they rise just after midnight (0h00 UT). The angular distance between the two is 2° (four moon widths)

Uranus, in western Aries, and Neptune in eastern Aquarius, are not suitably placed for observation during this month when twilight shortens the nights.

If you look at the sky in the early morning of the 6^th and the 7^th from 02h, you may see an increase in the number of shooting stars visible, until morning twilight becomes too bright. Earth is crossing the path of Halley’s comet, and tiny particles, debris from this famous ‘dirty snowball’ hit the upper atmosphere as the Eta-Aquarid meteors. This meteor stream is best observed from the southern hemisphere. The radiant, from which the meteors appear to come, is such, together with the twilight at this time of the year that very few eta-Aquarids are likely to be seen at the latitude of Scarborough in the northern hemisphere.

Constellations visible in the south around midnight, mid-month, are as follows: Libra, Scorpius, Serpens Caput (the serpent’s head) and Corona Borealis.

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