The month of May is named after Maia, a goddess of growing plants. The first day of this month, May Day, marks the halfway point of spring into summer. This will be a great time to get outside, and admire and learn more about all the celestial events always going on above us, as it will finally warm up consistently this month.

The major highlights this month include Venus at its best and brightest for the year in the morning sky; Jupiter just past its best for the year in the evening sky; some nice conjunctions of the moon with Venus, Mars and Mercury; Saturn rising earlier each night and approaching its opposition next month; the brightest asteroid, Vesta, visible in Cancer; not one, but two comets that could become visible to the naked eye; and the first good meteor shower of the year, the Eta Aquarids, caused by Halley’s Comet.

Venus has been a morning planet since the end of March, and it will reach its brightest for this year in early May while it is still similar to a waxing crescent moon. Venus will get a little smaller and become exactly half illuminated by the sun, similar to a third-quarter moon, in early June. Look for a waning crescent moon to pass just below Venus half an hour before sunrise on the 22nd and just below Mercury the next two mornings.

Jupiter is just past opposition now, but it is still brighter and closer than usual. The king of the planets continues to rule the evening sky, shining at minus 2.4 magnitude, exactly 4 magnitudes, or 39 times brighter, than the other evening planet, which is Mars in Taurus. Jupiter is in retrograde, or westward motion, against the fixed background of stars, and about 10 degrees above Spica, which is the brightest star in Virgo and the 16th-brightest star in our sky at first magnitude, or about 20 times fainter than Jupiter.

Spica is an extremely interesting double- or even triple-star system. The main component is a blue giant star about 260 light years away and 10 times more massive than the sun and thousands of times more luminous. The secondary component star is 10 times closer. They both orbit a common center of gravity, called a barycenter, every four days. This creates very strong tidal forces on all of the stars in this system, causing them to spin very rapidly, almost 100 times faster than our sun.

So when you look at Jupiter this month, remember that it’s less than one hour away at the speed of light, but that the light you are seeing from that rapidly whirling double or triple star just below it left there 260 years ago.

Mars continues to fade a little in Taurus and will pass just above Aldebaran, an orange giant star marking the eye of Taurus, in early May. Aldebaran is 44 times larger than our sun and probably has at least one Jupiter-sized planet. Pioneer 10, our first deep-space probe launched in 1972, will pass fairly close to this star in about two million years if no one intercepts it before then. So when you look at these two orange objects in the sky this month, remember that Mars is only 20 minutes away at the speed of light, but that Aldebaran is 65 years away.

Saturn now rises before midnight, at about the same time that Jupiter reaches its highest point in our sky. Saturn is in the constellation of Sagittarius. The ringed planet is already in retrograde motion and continues to get a little brighter and closer each night, heading toward its opposition in mid-June. At zero magnitude, Saturn is about 10 times fainter than Jupiter, but five times brighter than Mars.

The brightest of our asteroids, Vesta, can be seen just above the Beehive star cluster in Cancer this month. This cluster is related to the Hyades star cluster in Taurus, where Mars can be found for part of this month. You will need a good pair of binoculars or a small telescope to see this bright asteroid, since it will only reach eighth magnitude, or more than six times fainter than anything you could see without optical aid. At about 330 miles in diameter, about the size of Arizona, Vesta is the second-largest of our asteroids after Ceres, which is 600 miles in diameter, or about the size of Texas.

Comet 41P/Tuttle-Giacobini-Kresak is perfectly placed for viewing high in our night sky all month. It is passing fairly close to Earth now in its six-year orbit around the sun. It could even reach sixth magnitude in early May, which means you could see it without binoculars. I would recommend using binoculars to find it and then challenge yourself to see it without them. It is in Hercules now, passing just to the right of Vega, the brightest star in Lyra and the top of the summer triangle.

The second comet that could become bright enough this month is called Johnson(C/2015 V2). This is a first-time visitor to our solar system, so it is more unpredictable. Its tail is now wedge-shaped, but it should become much longer and more distinct in a few weeks in the constellation of Bootes the Herdsman.

There is even a third comet that now glows around seventh magnitude, or 21/2 times fainter than the human eye can see. This one is called Comet Panstarrs, low in the east near Venus before dawn. All three of these fairly bright comets will greatly fade out by the end of summer, so try to find them and photograph them this month or next.

The first good meteor shower of the year, called the Eta Aquarids, will peak on Saturday morning, the 6th. Caused by the most famous of all comets, Halley’s, you can expect about 50 meteors per hour that morning. Look for nearly half that rate each morning from the 3rd through the 10th. The moon will set around 4 a.m., which is the best time to see the most meteors anyway because the Earth is spinning into the meteors after midnight and toward dawn. They will all appear to emanate from Aquarius, hence the name. Aquarius is on the ecliptic just below the Summer Triangle and is up low in the east-southeastern sky by 4 a.m. These tiny, sand-grain sized pieces of Halley’s Comet will slash into our upper atmosphere at 40 miles per second, or more than twice the speed that the Earth is always orbiting around the sun. That makes them the fastest of all meteor showers, and they often leave very dramatic long, twisting trails that can be seen for several seconds.


May 2: First-quarter moon is at 10:47 p.m.

May 4: The moon passes less than one degree south of Regulus, the brightest star in Leo.

May 5: In 1961, Alan Shepard became the first American in space, aboard Freedom 7. He did not orbit the Earth, and that flight was just over three weeks after Yuri Gagarin did orbit the Earth. The first American to orbit the Earth was John Glenn on Feb. 20, 1962, aboard the Mercury Friendship 7 capsule.

May 7: The moon passes near Jupiter and Mars passes near Aldebaran tonight.

May 10: Full moon is at 5:42 p.m. This is also called the Flower, Milk or Planting Moon.

May 12: The Adler Planetarium, the first one in the Western Hemisphere, opened in 1930.

May 13: The moon passes near Saturn tonight.

May 14: Skylab was launched in 1973.

May 18: Last-quarter moon is at 8:33 p.m.

May 22: The moon passes near Venus this morning.

May 25: New moon is at 3:44 p.m.

May 28: The first primates, Able and Baker, were launched into space in 1959.

May 29: In 1919, Einstein’s General Theory of Relativity was tested and proved during a total solar eclipse in Africa and South America.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.