SkyEye

The Calendar

Look out for the η Aquariid meteors during the early part of the month when the skies are dark. The waxing crescent Moon passes through the open cluster M44 (Praesepe) on 11 May.

The Solar System

The word planet is derived from the Greek word for 'wanderer'. Unlike the background stars, planets seem to move around the sky, keeping mostly to a narrow track called the ecliptic, the path of the Sun across the stars. Dwarf planets and small solar-system bodies, including comets, are not so constrained, often moving far above or below the ecliptic.

Sun Aries → Taurus

Mercury Pisces → Aries → Taurus

Mercury soon disappears from the dawn sky. Observers in southern latitudes may be able to view the close pairing of Mercury and Uranus on 8 May but both planets will be very low in the sky. Superior conjunction occurs on 21 May and Mercury reaches perihelion three days later.

Venus Pisces → Aries

The morning star continues to dazzle southern hemisphere observers, shining at magnitude −3.9 and rising as much as two hours before the Sun. Planet watchers in tropical and southern latitudes will have the best chance of seeing bright Venus and faint Uranus together in the sky on 18 May when they come within 1.1° of each other.

Earth and Moon

The light from the very young crescent Moon poses no problems for observing the η Aquariid meteor shower on 6 May and the nights either side. On 11 May, the waxing crescent Moon occults M44, Praesepe, also known as the Beehive Cluster. Seven days later, the Moon is full, making it the third Full Moon of four in an astronomical season. This is a traditional Blue Moon as originally defined in eighteenth-century farmers' almanacs.

Mars Taurus → Gemini

Mars reaches maximum declination north this month. It is best viewed from northern latitudes but sets before midnight.

Jupiter Ophiuchus

Jupiter and the Moon have another close call this month, with our satellite passing less than 2° north of the planet on 20 May. With opposition in June, Jupiter continues to brighten and reaches magnitude −2.5 this month. It rises before midnight and is best seen from southern latitudes and equatorial regions.

Saturn Sagittarius

The lunar occultations keep coming, with the Moon gliding in front of Saturn at about 20:00 UT on 22 May. This gas giant is slowly brightening and reaches magnitude +0.3 by the end of the month. Still a morning sky object for observers in northern temperate latitudes, Saturn now rises before midnight for those seeking it from the southern hemisphere.

Uranus Aries

As Uranus emerges from the Sun's glare into the dawn sky, it first passes Mercury on 8 May and then Venus ten days later. However, at magnitude +5.9, this green ice giant may be too faint to see in the twilight of the eastern horizon.

Neptune Aquarius

A small telescope is necessary to view the most distant planet in the solar system. Tropical and southern latitudes have the best views of eighth-magnitude Neptune where it is high above the eastern horizon before sunrise.