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Sunday 18 March 2018  •   1 Alder Moon 2018

Viewing the night sky in Alder Moon 2018

18 March - 15 April 2018

Map of night sky at full moon: 31 March, 12:37 UTC
Northern hemisphere perspective, aligned on the ecliptic. Morning sky to the left, evening to the right.

night sky map for Alder Moon 2018

Mercury is visible to northern hemisphere viewers at the start of the lunar month, in the western sky after sunset. The brighter planet Venus is nearby, making Mercury easy to find.

On the evening of 18 March, the very new crescent moon is below Venus and Mercury, and a little to the south. As seen from northern lands, Mercury is above and to the right of Venus. From the southern hemisphere, you may just be able to see Venus to the right of the moon immediately after sunset, but Mercury is out of view.

On 19 March, the moon is above the pair. Mercury is on its way back towards the horizon (and this side of the sun), and dims over the next few days, as it becomes more crescent-like as seen from Earth. Venus passes it on 20 March. From northern lands, look for Mercury about four degrees (eight moon widths) to the right of Venus in the west after sunset. After a couple more days, it becomes hard to see in the twilight. Venus continues to rise slowly above the sunset, and in the early hours of 29 March, out of sight of Europe, but visible from much of North America, it passes just four minutes of arc south of Uranus, easily inside the same binocular and small telescope field. Uranus is just too faint to be seen with the naked eye under normal conditions. As seen on the evening of 28 March from Europe, Venus is 15 minutes of arc from Uranus.

Jupiter is bright and prominent in the night and morning sky, albeit relatively low down as seen from the northern hemisphere. It rises in the late evening. On the night 3/4 April, the moon is nearby.

Rising in the early hours are Mars and Saturn. At the start of the lunar month the planets are about the same brightness, though Mars should appear the redder of the two. Mars is further out from the sunrise, rising first. As the month proceeds, Mars approaches the ringed planet in the sky, and also gets brighter as in fact it gets closer to Earth. Watch as they change from night to night. On 2 April, Mars passes just over a degree south of Saturn in the constellation Sagittarius. On the mornings of 7 and 8 April, the moon is near the Mars-Saturn pair. Mars is by then noticeably brighter than Saturn and nearer the horizon.

Mercury passes this side of the sun on 1 April, and appears in the southern hemisphere’s morning sky in the last week of the lunar month. On the morning of 14 April, only visible from the south, the very old crescent moon is near Mercury.

The month ahead: Willow Moon 2018

16 April - 15 May 2018

Map of night sky at full moon: 30 April, 00:58 UTC
Northern hemisphere perspective, aligned on the ecliptic. Morning sky to the left, evening to the right.

night sky map for Willow Moon 2018

Venus continues its journey away from the far side of the sun and into our evening sky. On the evening of 17 April, the new crescent moon is below the bright planet. On 27 April, Venus passes between the Pleiades and Aldebaran, the bright star of Taurus.

Jupiter is very prominent all night, albeit relatively low down as seen from the northern hemisphere. It rises earlier and earlier in the evening, until on 9 May it is opposite the sun and rises around sunset. It is closest to Earth on 10 May, at 658 million kilometres, or 36.6 light minutes. Look through binoculars or a small telescope to see its four main moons, Io, Europa, Ganymede and Callisto, as they change position from hour to hour. With a slightly larger telescope, look for the red spot. For half an hour either side of 23:00 (22:00 UTC) on 9 May, you can see both the spot and the moon Io (along with its shadow) crossing the face of the planet. On the evening of 30 April, the moon is near Jupiter.

At the start of the lunar month, Mars and Saturn are together in the morning sky, in the constellation Sagittarius, with Mars the brighter of the two, and nearer the horizon. They rise an hour or two after midnight. During the course of the month, both planets brighten as they come towards opposition as well, but Mars brightens more noticeably. Mars also gradually moves away from Saturn, so that by the end of the month it rises about an hour and a half after the ringed planet, depending on your location. On 15 May, Mars enters Capricornus. On the morning of 5 May, the moon is near Saturn, and on 6 May, the moon is near Mars. By the end of the month, Saturn rises before midnight.

On 29 April, Mercury reaches 27 degrees west of the sun in the eastern morning sky, a poor view from the north, but well seen from the southern hemisphere, where it can be seen all month before sunrise. On the morning of 13 May, as seen from the south, the old crescent moon is near Mercury. That morning, Mercury is also passing two degrees south of Uranus. This much fainter ice giant can be seen through binoculars.

Look out for the Lyrid meteors on the night 22/23 April, and for the Eta Aquarids on 6/7 May, in both cases especially after midnight.

William Morris
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