SkyEye

The Calendar

This month's Full Moon is totally eclipsed on 16 May. Saturn at quadrature always makes for an interesting telescopic target. A rare meteor storm may occur at the end of the month when the Earth passes through remnants of Comet 73P/Schwassmann-Wachmann 3.

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 Taurus

Mercury concludes its evening apparition this month, moving into retrograde motion on 11 May ahead of its inferior conjunction ten days later. It then embarks upon its next morning appearance. The tiny planet reaches another aphelion on 27 May.

Venus Pisces → Cetus → Pisces → Aries

Venus reaches aphelion, the point in its orbit when its farthest from the Sun, on 15 May. The waning crescent Moon occults the morning star on 27 May. Visible from southern Madagascar and parts of the Indian Ocean, the occultation begins around 00:30 UT. Venus remains quite low to the eastern horizon for early risers in northern latitudes but is high in the sky before sunrise for astronomers in the southern hemisphere.

Earth and Moon

The nearly New Moon occults Uranus twice this month, on 1 May and again on 28 May. Dark skies enhance viewing of the η Aquariids early in the month and a total lunar eclipse takes place on 16 May. The almost unknown τ Herculid meteor shower may make a surprise appearance at the end of the month. Peak activity is theorised to occur at 05:00 UT on 31 May, favouring observers in the Americas. The radiant of the shower should be approximately 6° north-northwest of Arcturus in the constellation of Boötes. However, it is unknown whether the debris trail left by Comet 73P/Schwassmann-Wachmann 3 will actually intersect Earth's orbit.

Mars Aquarius → Pisces

Mars called upon Saturn last month; this month it moves past a much-fainter Neptune (18 May) and a much-brighter Jupiter (29 May). All of these encounters occur after midnight, with southern hemisphere planet watchers getting much the best views in dark skies.

Jupiter Pisces

Jupiter and Mars are just over half a degree apart late in the month, with Jupiter the far brighter object (magnitude −2.2 versus first-magnitude Mars). The best views of this planet are from the southern hemisphere where it rises just after midnight and is well-aloft by sunrise.

Saturn Capricornus

Saturn remains a morning sky object as seen from northern temperate latitudes but rises in the late evening for observers in the southern hemisphere. This is the place to be to observe Saturn telescopically mid-month when it reaches west quadrature. At 90° away from the Sun, the shadows of the planet, rings and satellites are noticeably cast to one side.

Uranus Aries

Uranus is at conjunction this month and is lost in the glare of the Sun. Both of the lunar occultations this month occur during daylight hours.

Neptune Aquarius → Pisces

A small telescope is necessary to view the most distant planet in the solar system. Neptune is visible in the morning sky, well aloft for southern hemisphere observers (it passes into the evening sky late in the month) but remains mired in dawn twilight for planet watchers farther north. Mars pays a visit mid-May.