Sky This Week is brought to you in part by Celestron.
Friday, May 2
Asteroid 4 Vesta reaches opposition at 2 A.M. EDT this morning. The magnitude 5.7 main-belt world is visible all night throughout the month of May, arcing slowly through Libra the Balance. The best time to view it is overnight around local midnight, when it is high in the south.
But you don’t have to stay up late if you want to observe the fourth asteroid ever discovered. Rising around 7 P.M. local daylight time, Vesta reaches an altitude of some 30° above the southeastern horizon by 10 P.M. local daylight time. It lies near the border of Libra and Virgo, just 2.5° northeast of 4th-magnitude Mu (μ) Virginis.
There’s very little in the way of background stars to interfere here, so Vesta can be quickly picked up in binoculars or any small scope. Circling the Sun every 3.63 years, Vesta lies just over twice as far from the Sun as Earth. It was the first of two asteroids visited by NASA’s Dawn spacecraft, which spent time studying the large asteroid from July 2011 to September 2012.
Sunrise: 5:58 A.M.
Sunset: 7:56 P.M.
Moonrise: 10:00 A.M.
Moonset: 1:02 A.M.
Moon Phase: Waxing crescent (31%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.
Saturday, May 3
The Moon passes 2° north of Mars at 7 P.M. EDT. An hour after sunset, both are high in the west, hanging in central Cancer the Crab. The waxing crescent Moon makes a lovely pair with the planet, and as the sky continues to darken there’s a bonus: Mars is just skirting the edge of the Beehive Cluster (M44), a bright open cluster visible to the naked eye and glittering readily through any optics.
The Red Planet is some 40’ north of the cluster’s center this evening, setting up an exquisite scene for astrophotography. Long-exposure landscape photos can capture the Moon, Mars, and Beehive all together in the sky, while pairing your camera with a telescope will show the ruddy planet amid the sparkling blue-white stars of the cluster. Mars now shines at 1st magnitude as it brushes the edge of the 3rd-magnitude cluster. Some 40 of the Beehive’s stars are visible with binoculars, while higher magnifications will bring out hundreds of the group’s stars, which ultimately number roughly 1,000. Only the brightest will appear tonight, given the nearby Moon, but there are still plenty of young suns on display long after sunset for springtime observers to enjoy.
Late this evening, Venus passes 2° north of Neptune at 11 P.M. EDT while both worlds are below the horizon. We’ll catch up with these two planets in the early-morning sky later this week.
Sunrise: 5:57 A.M.
Sunset: 7:57 P.M.
Moonrise: 11:11 A.M.
Moonset: 1:47 A.M.
Moon Phase: Waxing crescent (41%)
Sunday, May 4
For just a few more days, lucky observers may be able to spot the shadow of Saturn’s rings on the planet’s cloud tops.
To do so, you’ll want as large a telescope as possible and clear, steady air. The latter is a bit challenging no matter your equipment, as Saturn is rising shortly before the Sun and doesn’t get very high before the sky begins to grow light. Nonetheless, if you’re up for the challenge try centering your scope on Saturn about an hour before sunrise, when the planet is some 8° high in the east, to the lower right of blazing Venus in Pisces.
Saturn shines at magnitude 1.2, easy to pick up with the naked eye and readily visible through any telescope — although again, to catch a glimpse of the ring shadow you’ll want as big a scope as possible. The planet’s disk stretches some 16” across, with the rings tilted just 2° to our line of sight. Blurring from Earth’s atmosphere will make the endeavor even harder, but if you get a moment of steady air and have sharp eyes, you might just spot the rings’ shadow on the planet. Astronomy contributor Stephen James O’Meara recommends glancing toward the bright ends, or ansae, of the rings, to try viewing the nearly edge-on rings and shadow effects — including some optical illusions they create — on the planet out of the corner of your eye. Alternatively, high-speed video photography might yield good results for those experienced with the technique.
Related: Do Saturn’s rings cast shadows?
Regardless of whether you can make out their shadow, do pay attention to the appearance of Saturn’s rings. The planet is quickly approaching its equinox in just a few days and Earth crossed the plane of the rings just two months ago, so the world’s appearance is both particularly unique and also changing as we progress from the ring-plane crossing.
Later this morning, the Moon reaches First Quarter at 9:52 A.M. EDT.
Sunrise: 5:56 A.M.
Sunset: 7:58 P.M.
Moonrise: 12:20 P.M.
Moonset: 2:22 A.M.
Moon Phase: Waxing gibbous (51%)
Monday, May 5
Look west this evening after sunset to catch a glimpse of bright Jupiter, slowly setting between the horns of Taurus the Bull. An hour after sunset, Aldebaran — the Bull’s eye — is getting low, but Jupiter remains some 20° high.
With a telescope, center the stately gas giant in your field of view. It’s the brightest point of light in Taurus, easy to identify. The planet spans 33” and is flanked by its four Galilean moons early in the evening: Callisto far to the west with Europa nearer to the limb, while Io sits close to Jupiter to the east and Ganymede is farther out.
But there’s a disappearing act coming up: As time ticks by, you’ll see Europa getting closer to the planet, slipping behind the northwestern limb in an occultation at 10 P.M. CDT. The farther west you are, the better — Jupiter has already set for those in the Eastern time zone and is very low in the Midwest, while it remains respectably high above the turbulent air near the horizon farther west.
The Eta Aquariid meteor shower peaks overnight tonight, with the radiant rising in the early-morning hours of the 6th. Late-night observers might catch an increasing number of meteors as midnight approaches and the calendar date changes — keep reading for more details on where to find the radiant and the best time to watch the stunning shower in tomorrow’s entry.
Sunrise: 5:55 A.M.
Sunset: 7:59 P.M.
Moonrise: 1:27 P.M.
Moonset: 2:50 A.M.
Moon Phase: Waxing gibbous (62%)
Tuesday, May 6
This morning is the best time to catch the Eta Aquariid meteors, born from the debris left by the famous Halley’s Comet.
The shower’s radiant lies in Aquarius, just to the lower left of the 3rd-magnitude star Sadalmelik as the constellation rises a few hours after midnight. That’s fine, though, because the best time to watch a meteor shower is in the early morning, as the hemisphere you’re on rotates into the stream of debris as Earth orbits the Sun.
By 4:30 A.M. local daylight time, the radiant has reached some 20° high in the east, with about 10 meteors per hour likely visible. Eta Aquariid meteors are known for their lingering trains as they streak through the atmosphere, offering a stunning predawn sight for those willing to get up early.
Pluto stands stationary this morning at 2 A.M. EDT against the background stars of Capricornus.
Additionally, Saturn experiences its equinox as the Sun crosses the planet’s equator. The rings’ shadow completely disappears as a result.
Sunrise: 5:54 A.M.
Sunset: 8:00 P.M.
Moonrise: 2:29 P.M.
Moonset: 3:14 A.M.
Moon Phase: Waxing gibbous (71%)
Wednesday, May 7
Let’s check back in with the morning sky today, where Venus blazes a bright magnitude –4.7. To its right, 1st-magnitude Saturn is also readily visible to the naked eye, while elusive Neptune lies between them. You’ll have a brief opportunity to catch the distant magnitude 7.8 ice giant in your sights with binoculars — or, better yet, a telescope — about an hour before sunrise, while the sky is still dark.
Start your search at Venus, whose 33”-wide disk (as large as Jupiter, thanks to Venus’ much closer proximity to Earth) shows off a 33-percent-lit crescent. Neptune lies just 3.2° southwest (to the right) of Venus in the sky and is best seen while the background is still dark, before dawn encroaches too much. Neptune’s apparent size is just 2”; you’re looking for a faint, “flat” star that appears more circular than pointlike and might have a bluish-gray cast to its color.
Finally, as you lose Neptune in the oncoming dawn, take a quick peek at Saturn, just 2.9° farther southwest of Neptune (and easy to center on because it’s visible to the naked eye). The ringed planet is showing off the sunlit southern side of its rings, which stretch some 37” from end to end. East Coast observers might just catch a glimpse of the planet’s brightest moon, Titan, which disappears into the world’s long, dark shadow just before 5:20 A.M. EDT — shortly after the planet has risen in the Midwest and is likely still too low for clear views, although those in the eastern portions of the Central time zone may have some luck.
Sunrise: 5:53 A.M.
Sunset: 8:01 P.M.
Moonrise: 3:31 P.M.
Moonset: 3:35 A.M.
Moon Phase: Waxing gibbous (79%)
Thursday, May 8
This morning’s object is high in the southern sky around 4 A.M. local daylight time. It is the stunning Swan Nebula (M17), also known as the Omega Nebula. It glides serenely through northern Sagittarius, far above the spout of the Teapot asterism as it sits right-side up in the sky this morning.
With no Moon above the horizon, if you’ve got a dark sky you might be able to spot this lovely nebula with binoculars — it glows at magnitude 6. It lies near the border that Sagittarius shares with Scutum and Serpens Cauda; look for M17 just 2.6° southwest of magnitude 4.5 Gamma (γ) Scuti.
Spanning some 11’, the Swan Nebula looks like its namesake, with a long flat “body” capped at one end by an arched “neck.” It may also appear a bit like the number 2 or even a checkmark, depending on your conditions and visual acuity. A telescope equipped with an OIII filter might help bring out the view. If you’ve got a large (8- or 10-inch) scope, you might be able to tease out a mirror-image extension of that curved neck, which turns the swan into the Greek letter Omega (Ω), hence the nebula’s other name.
Sunrise: 5:52 A.M.
Sunset: 8:02 P.M.
Moonrise: 4:30 P.M.
Moonset: 3:54 A.M.
Moon Phase: Waxing gibbous (86%)
Friday, May 9
Asteroid 9 Metis reaches at opposition at 2 A.M. EDT in the constellation Libra — not far from Vesta, which reached opposition a week ago. Visible from sundown to sunup, the best time to look for Metis is around local midnight, when it is transiting and stands highest in the southern sky.
Metis is shining at magnitude 9.7, much fainter than Vesta. Still, binoculars or any small scope should show it some 4.4° east-northeast of Zubenelgenubi, Libra’s stunning double alpha star. Zubenelgenubi is a great stop on the way to viewing Metis, as the 4’-wide pair of suns is easy to split with any optics. The brighter component shines at magnitude 2.8, while the fainter star is magnitude 5.2.
Also take a moment to visit brighter Vesta, which has now moved into Virgo and stands just under 2° north-northeast of Mu Virginis. In two days’ time, Vesta will stand due north of this star, so it’s a great signpost to measure the bright asteroid’s motion over the course of just a few days.
Sunrise: 5:51 A.M.
Sunset: 8:03 P.M.
Moonrise: 5:30 P.M.
Moonset: 4:13 A.M.
Moon Phase: Waxing gibbous (92%)
