May 3, 2017
First Quarter Moon Looks Great, Bino Comets continue, Weekend Meteors, and Saturn Joins the Evening Sky!
Public Events
Taking advantage of the Moon and some favorite objects in the sky this week, the RASC Toronto Centre astronomers will hold their free monthly public City Sky Star Party in Bayview Village Park (steps from the Bayview subway station), around 7:30 pm on the first clear weeknight this week (Mon to Thu). You don’t need to be an RASC member, or own any equipment, to join in. Check here for details, and check the banner on their website home page or Facebook page for the GO or NO-GO decision around 5 pm each day.
The RASC Mississauga Centre astronomers are holding their own public stargazing on Tuesday evening with a backup date on Wednesday. Details are here.
On Wednesday, May 3, the Perimeter Institute in Waterloo is presenting a free public lecture (reservations required) by Professor Jana Levin of Columbia University, speaking about Black Holes and Other Songs from Space, the new era of gravitational wave astronomy. The lecture will also be streamed live. Details are here.
On Thursday afternoon, May 4 from 1:30 pm, the U of T Department of Physics presents the annual free public Welsh Lectures. This year’s topics are Gravitational Waves and Quantum Physics Weirdness. Details are here.
If it’s sunny this Saturday, May 6th from 10 am to noon, members of the RASC Toronto Centre will be setting up outside the main doors of the Ontario Science Centre for free Solar Observing. Come and see the Sun in detail through special equipment designed to view it safely. This is a monthly event that is free to the public (details here), but parking and admission fees inside the Science Centre will still apply. Check the RASC Toronto Centre website or their Facebook page for the Go or No-Go notification.
Binocular Comet Update
The comets I’ve been mentioning recently are still observable in binoculars and low power telescopes, although the moon will hamper things this week. Expect the comets to appear as faint greenish blobs (quite different from a star). If they develop a tail, it will point roughly away from the Sun.
Comet 41P/Tuttle-Giacobini-Kresak is an all-night comet visible as soon as it’s fully dark, but highest in the sky before dawn. It has peaked in brightness, in the binocular range. This week, the comet is in the eastern evening sky and dropping lower, passing between the bright star Vega and the constellation of Hercules. Keep an eye on it — this comet has a reputation for sudden outbursts that dramatically brighten it.
Comet C/2015 ER61 (PANSTARRS) is a pre-dawn comet in the eastern sky that is moving eastward (towards the left) from Aquarius (the Water Bearer) towards Pisces (the Fishes), in the region of sky to the upper right of Venus. It has already brightened past its expected peak.
Comet C/2015 V2 (Johnson) is also still brightening. This week, it starts moving southwest, from the top of Hercules in a direction towards the bright star Arcturus. Look above the eastern horizon in mid-evening, and nearly overhead in the wee hours. Being near the pole star, this comet stays up all night.
Eta Aquariid Meteor Shower
The annual Eta Aquariid Meteor Shower runs from April 19th to May 26th and peaks before dawn on Sunday this coming weekend. Viewing is best for southern hemisphere observers, but northerners can see as many as a few dozen per hour near the peak. These are fast meteors with persistent trails, and a few fireballs. The source of the shower is material that has been shed during repeated passages of Halley’s Comet. You can look for the meteors anywhere in the sky, but they will appear to radiate from low in the eastern pre-dawn sky in the constellation of Aquarius (the Water-bearer). Unfortunately, the moon is nearing full at the peak, leaving the sky less than ideal.
The Moon and Planets
The moon reaches First Quarter on Tuesday evening, the point in its monthly orbit when it sits at a right angle from the Sun and Earth. This geometry causes the moon to be illuminated 50–50. The word “quarter” refers to the amount of the moon’s journey it has completed — not the shape of the moon’s lit area. The evenings around first quarter are the best times to observe the moon. It rises around noon time and sits conveniently in the western evening sky after dusk. And the steep angle of the sunlight shining along the terminator boundary (separating the lit and dark areas) casts dramatic shadows easily visible in binoculars and telescopes.
As the week unwinds, the moon will wax fuller and shift east, rising later every day. On Wednesday night, the moon will land about 4° (a few finger widths) to the right of the bright star Regulus, the heart of Leo (the Lion). On Sunday, May 7, Jupiter, the nearly full moon, and the bright star Spica will appear together in the eastern sky after dusk. The moon and Jupiter will fit within a binocular field of view and make a nice photo opportunity. The three objects will cross the night sky together and be visible low in the western sky before 5 am local time.
Mercury has moved into the eastern morning sky for month, but the sky is too bright to easily see it this week. Venus, however, is the eye-catching object dominating the morning sky. It reached maximum brightness on Sunday. This week, it rises about 4:30 am local time and lasts well into dawn. In fact, it’s possible to see Venus in broad daylight, if you know where to look. For example, right now Venus is about 40° west of the sun, and close to the ecliptic. The next sunny day, try looking along the ecliptic about four outstretched fist diameters to the right of the sun for Venus’ tiny bright speck. If you use binoculars, be sure to keep them pointed well away from the sun!
Yellowish Saturn becomes an evening object this week, finally rising in the southeast before midnight local time, and visible until dawn, when it’s two fist diameters above the southern horizon. During this summer’s Saturn season, the ringed planet is in the Milky Way, above the large Teapot-shaped asterism in Sagittarius. The bright reddish star Antares in Scorpius (the Scorpion) is less than 20° to the right (southwest) of the planet, too.
Bright, white Jupiter is now an outstretched fist diameter to the upper right of Virgo’s (the Maiden) brightest star Spica. This week, the planet shines in the southeastern evening sky after dusk, reaches its highest point over the southern horizon at 11:30 pm, and sets in the west before dawn.
Jupiter and its four large Galilean moons are easily visible in a small telescope. A slightly larger telescope will also show the Great Red Spot and the round black shadows cast by Jupiter’s moons when they cross (or transit) the planet. Here are the best events in Eastern Daylight Savings Time. (Simply add or subtract the appropriate hours to convert them to your time zone.)
Io’s shadow crosses the planet on Wednesday, May 3 from 1:36 am to 3:47 am. It transits again on Thursday, May 4, starting in twilight and ending at 10:15 pm. The Great Red Spot is visible on Jupiter for about three hours centred on Monday, May 1 at 10:42 pm, on Thursday, May 4 at both 12:20 am and 8:12 pm (in twilight), and on Saturday, May 6 at both 1:59 am and 9:60 pm.
Reddish Mars, about a palm’s width to the right of the bright orange star Aldebaran in Taurus (the Bull), is gradually sinking into the evening twilight, setting about 10:30 pm local time this week. While similar in appearance, the distant star will outshine the red planet. During the week, you’ll be able to notice Aldebaran dropping lower than Mars.
Keep looking up to enjoy the sky! Stargazing News for this week (from May 30th) by Chris Vaughan.
