Ian Morison tells us what we can see in the Northern Hemisphere night sky during May 2019.
- Jupiter, starts the month shining at magnitude -2.5 which increases to to -2.6 as the month progresses. At the same time, its angular size increases from 43 to 46 arc seconds. As May begins it rises by midnight UT so will be due south around 3 am UT whilst at month's end it rises at ~9:30 pm UT so due south at ~01:30 UT. See the highlights fro when the Great Red Spot faces the Earth. Sadly it is heading towards the southernmost part of the ecliptic and currently lies in the southern part of Ophiuchus just above Scorpius so, as it crosses the meridian, it will only have an elevation of ~ 14 degrees. It lies just above the centre of the Milky Way. Atmospheric dispersion will thus take its toll and an atmospheric dispersion corrector would greatly help to improve our views of the giant planet.
- Saturn, shining with a magnitude increasing from +0.5 to +0.3 during the month, rises around midnight during the month so crosses the meridian just before dawn. Its disk is ~18 arc seconds across and its rings - which are still nicely tilted from the line of sight - spanning 40 arc seconds across. Morning twilight is the best time to observe it but, sadly, now in Sagittarius and lying on the southern side of the milky way, it is at the lowest point of the ecliptic and will only reach an elevation of ~10 degrees. As with Jupiter, an atmospheric dispersion corrector will help improve our view.
- Mercury, passes through superior conjunction (behind the Sun) on May 21st and will only be visible, low in the west-northwest, on the last few days of the month. One will need a very low horizon and binoculars could well be needed to reduce the Sun's background glare, but please do not use them until after the Sun has set.
- Mars, though fading from +1.6 to +1.8 magnitudes during the month, is still visible in Taurus in the south western sky after sunset lying half way between Betelgeuse, in Orion, and Capella, in Auriga. Mars sets some three hours after the Sun at the start of May (with an elevation as darkness falls of ~20 degrees) but less than two and a half hours by month's end. Its angular size falls from 4.2 arc seconds to less than 4 arc seconds during the month so one will not be able to spot any details on its salmon-pink surface.
- Venus, has a magnitude of -3.8 in May with its angular size reducing from 11.5 to 10.8 arc seconds during the month as it moves away from the Earth. However, at the same time, the percentage illuminated disk (its phase) increases from 88% to 92% - which is why the brightness remains constant at 3.8 magnitudes. It rises about an hour before the Sunbut its elevation is only ~4 degrees at sunrise so a very low horizon in the East is required and binoculars may well be needed to spot it through the Sun's glare - but please do not use them after the Sun has risen.
- May 7th - after sunset: Mars lies above a thin crescent Moon. Given a low horizon looking towards the west after sunset one should, if clear, be able to spot Mars lying halfway between Betelgeuse and Capella above a very thin crescent Moon.
- April 12th - evening: The Moon in Leo Looking southwest in the evening a first quarter Moon will be seen lying close to Regulus in Leo.
- May 19th - early evening: Mars above M35 in Gemini. Looking west in early evening if clear, and using binoculars or a small telescope one could see Mars lying just above the open cluster, M35, in Gemini. Perhaps a last chance to see Mars at the very end of its apparition.
- May20th - midnight: Jupiter and the Moon. During the night of the 20 May, Jupiter will lie over to the right of the waning gibbous Moon.
- May 23rd - early morning: Saturn and the Moon. In the early Morning of the 23rd of May, Saturn will lie up to the right of the waning gibbous Moon.
- May 28th - around midnight: spot asteroid 1, Ceres. On the 28th May, Ceres is at its closest approach to Earth lying over to the right of Jupiter. It will have a magnitude of 7 so binoculars should enable you to spot it and the chart will help you find it. A planetarium program such as Stellarium will show you its position in the days before and after its closest approach. Ceres is the largest of the minor planets and is now classified as a 'Dwarf Planet'.
Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speak about the Southern Hemisphere night sky during May 2019.