This Month’s Sky – May 2016


What’s Up in the Sky
AAA Observers’ May Guide
By Tony Faddoul

May’s Evening Planets: Jupiter will be in Leo the Li-on all night this month. Mars will be in Scorpio the Scorpion and Saturn can be found between Scorpio and Ophiuchus the Serpent Bearer as of 10:00 PM, rising earlier every night.

May’s Evening Stars: Spot Spica in Virgo the Virgin, Arcturus in Boötes the Herdsman, Vega in Lyra the Harp, and Castor and Pollux in Gemini the Twins. Also find the stars of constellations Cassiopeia, Virgo, Hercules, Ophiuchus, Libra, Leo, Cancer, Hydra, and Ursa Major and Ursa Minor (the Big and Little Dippers) in May.

May’s Morning Planets: Mars will be in Scorpio and Saturn will be between Scorpio and Ophiuchus until sunrise. Jupiter can be seen in Leo until 4:00 AM and setting earlier every night until 2:00 AM by the end of May. Uranus will be in Pisces the Fish about 2 hours before sunrise, and Nep-tune is in Aquarius the Water Bearer beginning at 4:00 AM, rising earlier every night. Mercury is in Cetus the Sea Monster as of 5:00 AM in the second half of May. Dwarf Pluto is in Sagittarius the Archer from 1:00 AM until sunrise.

May’s Morning Stars: Spot the Summer Triangle of Vega in Lyra the Harp, Deneb in Cygnus the Swan, and Altair in Aquila the Eagle as of midnight and rising earlier eve-ry night. This month, look for reddish Antares in Scorpius and Arcturus in Boötes, along with the stars of constellations Hercules, Libra, Scorpius, Sagittarius, Pegasus, Andromeda, Capricornus, Ophiuchus, Cassiopeia, Draco, Ursa Major, and Ursa Minor.

May Skylights
May 5 Eta Aquariid meteor shower peaks dawn
May 6 Moon at perigee (222,300 miles away)
May 6 New Moon at 3:30 PM
May 8 Aldebaran is 0.5° south of Moon dawn
May 9 Jupiter is stationary sunset
May 13 First Quarter Moon at 1:00 PM
May 15 Jupiter is 2° north of Moon sunrise
May 18 Moon at apogee (252,200 miles away)
May 21 Full Moon at 5:15 PM
May 21 Mercury is stationary sunset
May 22 Mars is at opposition sunrise
May 29 Last quarter moon at 8:12 AM
May 30 Mars is closest to Earth (46.8 M miles away)

Times given in EDT.


A Bright Mars in May

This month presents a great opportunity for viewing neighbor planet Mars. In opposition on May 22, the Red Planet will shine brighter in the night sky than it has in over a decade at magnitude -2.1, and it makes a close approach on May 30.

What is opposition?
Opposition occurs when a planet is directly opposite the Sun from Earth’s perspective – a straight line is formed between the planet and the Sun, with the Earth between the two. This year, Mars’ opposition happens when it is very close to the Earth in its orbit, which makes it appear brighter and larger in our sky. Mars, the fourth brightest object after the Moon, Venus, and Jupiter, will be nearly as bright as Jupiter in May.

How close will Mars be?
About a week after opposition, Earth and Mars will make a close approach. Mars will be 46.8 million mi away on May 30. Nearer the Sun, Earth orbits faster than Mars, but the two catch up about every 26 months. This happens at various points along their elliptical orbital paths, so close approach distances change. On July 31, 2018, Mars will be very close at only 35.8 million mi away, making for exceptional viewing. It won’t be that close again until 2035. The nearest it can come is 33.9 million mi, when Mars is at its perihelion (closest to the Sun) and Earth is at its aphelion (furthest from the Sun) during a close approach, which is rare.

Where can I find Mars?
On May 21, Mars will rise in the east around sunset in the constellation Scorpius, climbing to its highest point in the sky at midnight for opposition, still fairly low above the horizon. Mars will shine brightly, despite a Full Moon, and set in the west by sunrise on May 22. Reddish Mars will be close to red star Antares, the brightest star in Scorpius. It will also be close to bright planet Saturn.

How did Mars get its name?
In Roman mythology, Mars is the god of war, known as Ares to the Ancient Greeks. Its color invokes bloodshed; however, Mars appears red due to the abundance of iron oxide in its surface dust. Its two moons, Phobos and Deimos, represent the twin gods of fear and terror, sons of Mars and Venus.

Sources: timeanddate.com; earthsky.org.