The Sky This Week: May 2 – May 8
Mars heads toward peak visibility, a young Moon shines faintly, and the Eta Aquariid meteor shower peaks.
Monday, May 2
Grab your binoculars tonight and target the bright star Regulus in Jupiter’s current home constellation, Leo the Lion. Many people know that this object represents the Lion’s heart, but few realize it also is a binocular double. Regulus B, which glows at 8th-magnitude, shows up as a pinpoint nearly 3′ from the 1st-magnitude primary. See “10 tempting spring binocular targets” in the May issue of Astronomy for other treats visible with just the slightest optical aid.
Tuesday, May 3
About 30 minutes after Mars rises, Saturn pokes above the southeastern horizon. Although the ringed planet pales in comparison to its neighbor, its yellow color contrasts nicely with the Red Planet’s hue. Throw in the ruddy glow of nearby Antares, the 1st-magnitude luminary of Scorpius, and you have a colorful trio of bright objects to follow throughout the late evening and morning hours. As you might guess, Saturn’s proximity to Mars means it also will reach opposition and peak visibility soon — in fact, it reaches this orbital highlight one month from today. The view of Saturn through a telescope never fails to impress. This week, the world appears 18″ across and sports a beautiful ring system that spans 41″ and tilts 26° to our line of sight.
Wednesday, May 4
Another comet in the growing throng of such objects discovered by the Pan-STARRS telescope in Hawaii makes its appearance in May’s morning sky. Comet PANSTARRS (C/2013 X1) currently glows at 7th magnitude near the border between Pisces and Aquarius. From most of the United States, you’ll need a clear, flat eastern horizon to spot the comet through a telescope just before dawn breaks.
Thursday, May 5
One of this year’s best meteor showers reaches its peak today. The Eta Aquariid shower derives from bits of debris ejected by Comet 1P/Halley during its many trips around the Sun. When Earth crosses this debris stream, our planet’s atmosphere incinerates the tiny dust particles and we see the streaks of light called meteors, or “shooting stars.” With New Moon arriving tomorrow, conditions are ideal. Shortly before dawn today and tomorrow, an observer at a dark site can expect to see up to 20 meteors per hour — an average of one every 3 minutes. Viewers in the Southern Hemisphere, where the shower’s radiant (in the constellation Aquarius) passes nearly overhead, should see twice as many.
Friday, May 6
New Moon occurs at 3:30 p.m. EDT. At its New phase, the Moon crosses the sky with the Sun and so remains hidden by our star. Because the Moon reaches perigee, the closest point in its orbit around Earth, only 15 hours earlier (at 12:13 a.m. EDT), residents in coastal areas can expect higher than normal tides for the next few days. At perigee, the center of the Moon lies 222,344 miles (357,827 kilometers) from Earth’s center.
Mars passes 1.2° north of the 7th-magnitude globular star cluster M80 tonight. The view through binoculars or a telescope at low power should be impressive.
Jupiter sports a pair of “black eyes” tonight as the shadows of two of its large moons cross the jovian cloud tops. The shadow of outermost Callisto treks across the planet’s north polar region from 11:18 p.m. until 1:42 a.m. EDT. Innermost Io’s shadow crosses the gas giant from 12:39 a.m. to 2:53 a.m. EDT. It’s easy to tell the two shadows apart because Io’s will appear much closer to Jupiter’s equator.
Saturday, May 7
With an age of 4.5 billion years, “young” might not seem an appropriate word to describe our Moon. But tonight, you have an exceptional opportunity to see what astronomers call a “young Moon” — a slender crescent visible low in the west some 30 to 45 minutes after sunset. With New Moon having occurred yesterday afternoon, only 2 percent of our satellite’s disk appears illuminated this evening. You should notice an ashen light faintly illuminating the Moon’s dark side. This is “earthshine,” sunlight reflected by Earth that reaches the Moon and then reflects back to our waiting eyes. Use binoculars for the best view. The young Moon will be much easier to see tomorrow evening, when it appears significantly higher and some 7 percent illuminated.
Sunday, May 8
Although the calendar says May, the sky’s Summer Triangle returns to prominence this month. The asterism’s three bright stars — Vega in Lyra, Deneb in Cygnus, and Altair in Aquila — all clear the horizon by midnight local daylight time. An hour later, they rule the eastern sky. Vega shines brightest and appears at the apex of the triangular asterism. Look for Deneb to Vega’s lower left and Altair to the lower right of the other two. The Summer Triangle will grace the Northern Hemisphere’s evening sky from now through the end of the year.
Source
Astronomy Magazine
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