Scobee Planetarium at San Antonio College

Welcome to the Skyline
Highlighting This Month’s Celestial Events

May Sun

Ah, the very merry month of May! You can’t help but notice the growing “power” of the Sun. Not only are the days becoming warmer, our star spends an ever increasing amount of time in the sky. Add to this the Sun’s escalating height above the noontime horizon, and no wonder the days are getting warmer!
May 1st marks the middle of the spring season. Six weeks have passed since the Vernal Equinox. Six weeks remain until the Summer Solstice and the longest day of the year arrives on June 21st. On May 1st the Sun spends 13 hours and 21 minutes above the horizon. By the end of the month the amount of possible sunshine swells to 13 hours and 54 minutes. The Sun also climbs higher above the noonday horizon, jumping from 74 degrees above the southern horizon to 81 degrees. Remember, that’s angle of measurement, not temperature.

May Moon

Our lunar companion begins the month of May in the morning sky. Look for a thin lunar crescent prior to sunrise on the mornings of May 1st through the 3rd. The Moon passes invisibly between the Earth and the Sun as it reaches New phase on May 5th. Returning to the evening skies, a razor-thin crescent Moon hovers near Mercury just after sunset on May 6th. Gliding eastward through the stars, the Moon shines below Mars on May 9th and then above Mars on May 10th. On May 12th, the First Quarter Moon shares the sky with Saturn. Brightening towards full phase, look for the Full Moon on May 19th. Thereafter, the Moon rises later and later each night. Prior to sunrise on May 24th, the Moon gleams alongside bright Jupiter. Last Quarter phase takes place on May 27th.

May Evening Planets

Mercury, the Sun’s nearest planet, emerges out of the solar glow to put on one of its best evening appearance of the entire year! During the first three weeks of May, Mercury can be glimpsed just above the sunset horizon. Appearing like a medium bright “star” against the backdrop of the evening twilight, at the middle of May, Mercury sets almost 2 hours after the Sun – the maximum ever possible for this planet! Be sure to look for a razor-thin lunar crescent alongside Mercury following sunset on May 6th. As May comes to an end, so does our view of Mercury as the planet retreats back into the solar glow.

Mars - Following sunset, the orange red sparkle of Mars is situated above the western horizon. Although the planet has lost much of its luster since last December’s “close encounter” with the Earth, Mars remains well placed in the evening skies. Mars begins May among the stars of Gemini the Twins, but by the middle of month, the red planet leaves the stars of the Twins and shifts into the neighboring constellation of Cancer the Crab. The Moon comes to visit Mars on the evenings of May 9th and 10th. Mars is also preparing for company. On May 25th, another visitor from Earth arrives. The Phoenix spacecraft lands near the northern polar cap of Mars. Good luck!

Saturn, the planet with the brightest rings, is well placed above the southern horizon following a May sunset. Situated near the bright star Regulus in the constellation of Leo the Lion, Saturn glows with a yellow-white color. In fact, this is the closest Saturn is to Regulus for the next 30 years. Saturn sets in the west at about 2:00am. Look for the Moon just above Saturn on the evening of May 12th. A small telescope shows a nice view of the planet’s ring and brightest moons. This beautiful planet remains our “prime” planetary target for our observatory telescope during the month of May.

May Morning Planets

Jupiter, the largest world of the Solar System, A small telescope easily reveals Jupiter's banded atmosphere and 4 largest satellites. Traveling through the stars of Sagittarius, the Archer, the planet Jupiter gleams with a silver-white luster. In May, Jupiter rises about 1:00am. At sunrise, Jupiter is well placed above the southern horizon. Jupiter is alone in the morning sky. With Venus lost in the glow of the Sun, Jupiter, the king of the planets, dominates the morning skies of May.

Venus, the Sun’s brightest planet, is lost in the solar glow for the next two months. This lovely planet will not become visible in the evening skies until late summer.

May Meteor Showers

After several quiet months of meteor watching, activity picks up with Eta Aquarid meteor shower that reaches peak activity on several nights around May 5th. This usually reliable shower produces 20 to 30 meteors per hour. The Eta Aquarid display is one of two meteor showers produced by the tiny particles of rock and ice left behind by Halley's Comet. The pleasant evenings of spring are often punctuated by the quick flash of a meteor streaking overhead.

Wishing you clear skies!

Bob Kelley
Scobee Planetarium Educational Specialist
San Antonio College
bkelley@mail.accd.edu or (210) 733-2913