Red and Black Spots on Sunday’s Jupiter, Ceres Peaks, and Old Moon gives Dark Sky Delights!
The Moon and Planets
The moon reaches its Last quarter phase today (Sunday) after mid-day, so it will be completely out of the evening sky throughout the world for the coming week. Last quarter moons always rise near midnight and then linger into the daytime morning sky, leaving the evening sky nice and dark for stargazers.
Over the next handful of days, the moon will swing towards the morning sun while passing through the water constellations of Aquarius (the Water-Bearer), Pisces (the Fishes), and Cetus (the Whale). On Saturday morning, the old, slim crescent moon will appear a palm’s width to the right (or southwest) of the bright planet Venus — with both objects among the stars of Aries (the Ram).
Due to its orbital inclination, the moon meanders up to 5 degrees away from either side of the ecliptic. The ecliptic’s circle around the sky traces the sun’s apparent path through the zodiac constellations. You might catch a final glimpse of the very slim moon sitting very low in the north-northeastern sky on Sunday morning.
Mars’ bright, reddish pinpoint will still be visible in the western evening sky for a short while after sunset this week. Mars will be slowly crossing the legs of Castor in Gemini (the Twins) and setting at about 11:15 pm local time. Look for the bright star named Mebsuta sitting to Mars’ upper right all week. That star is a yellow supergiant star located 840 light-years from our sun. The separation between Mars and Mebsuta will decrease during the week as Mars shifts eastward.
Wow! Jupiter has definitely made its entrance — shining as a blazing beacon of light in the eastern sky after it rises at about 9:30 pm local time. Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air).
If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet between 10:30 pm and 1:30 am EDT tonight (Sunday). As a fabulous bonus, from 12:08 am to 2:18 am Eastern Time, the round, black shadow of Jupiter’s moon Io will cross (or transit) the planet, too. The shadow will complete its crossing after the GRS has moved out of sight. More GRS viewing opportunities occur in the hours surrounding 2 am EDT on Wednesday morning, 10 pm on Wednesday evening, and 11 pm EDT on Friday.
Yellowish Saturn will be rising about 2 hours after Jupiter all summer, which positions it about 2.5 outstretched fist diameters to the lower left (east) of Jupiter in the pre-dawn sky. This area is just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). This week, Saturn will officially be part of the evening sky because it will be rising a few minutes before midnight. Dust off your telescope because even a small telescope will show its rings and several of its brighter moons!
Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will rise at about 2:30 am local time. But I’d wait for summer to look at it, when it will be available in the evening sky.
Our bright, next-door neighbour Venus is sitting low in the east-northeastern pre-dawn sky this week, creeping ever-closer to the rising sun. Meanwhile, Mercury is low in the western sky after sunset. It’s just beginning a good appearance for those viewing it from the Northern Hemisphere. The best period to see Mercury this week falls between 9 and 9:30 pm local time.
On Tuesday, May 28, the dwarf planet (formerly asteroid) Ceres will reach opposition, its closest approach to Earth for the year. On the nights around opposition, Ceres will shine with a peak visual magnitude of 7.1, well within reach of binoculars and backyard telescopes. As a bonus, Ceres will be situated only 1 finger’s width to the upper right (or northwest) of the modestly bright star named Xi Ophiuchi. Both objects will easily fit within the field of view of a backyard telescope, although your telescope will mirror and/or invert the binoculars view. To get you into the right patch of sky, Ceres will be located less than a fist’s diameter above the very bright, orange star Antares in Scorpius (the Scorpion). Ceres will reach its highest elevation, and peak visibility, over the southern horizon a little after midnight local time.
After a determined search by many astronomers who were looking for a theorized missing planet, Ceres was the first asteroid ever discovered, by Giuseppe Piazzi in Palermo, Sicily, on January 1, 1801. It was named after the Roman Goddess of Agriculture. (The same name gave us the word “cereal”!) Ceres was originally given planet status, orbiting as it does between Mars and Jupiter. But calculations of its 950 km diameter, and later discoveries of countless additional bodies in the asteroid belt, led to its demotion to queen of the asteroid belt. But in 2006, the same rules that demoted Pluto to dwarf planet status promoted Ceres up to the same class of objects. Let me know if you see it!
Dark Sky Delights
Throughout this week, the waning, late-rising moon will leave our evenings nice and dark, worldwide — ideal for hunting for dimmer targets such as the spring galaxies in Leo (the Lion) that are observable in backyard telescopes.
Here are some more objects.
As soon as the sky darkens after sunset, the bright star Arcturus pops into view high in the eastern sky, heralding the summer stargazing season. Four globular star clusters occupy the sky just to the right (west) of Arcturus. All four are visible as faint fuzzy patches in binoculars under dark sky conditions. At visual magnitude 6.2, Messier 3 is the brightest. It sits a generous fist’s diameter above Arcturus. Dimmer NGC 5466 is five finger widths to the lower left of Messier 3. Another bright globular designated Messier 53 sits 1.5 fist diameters to the right of Arcturus and only one finger’s width to the upper left of Diadem, which is Coma Berenices’ (Berenice’s Hair) brightest star. NGC 5053, the dimmest of the four globulars, is located a finger’s width to the lower left of Messier 53.
Planetary nebulae, a term coined because they visually resemble a small planet’s disk, are the corpses of stars that have a similar mass to our sun. These plentiful objects are distributed throughout the sky, and exhibit a wide variety of shapes and structures. The brightest planetaries visible on May evenings include the Ghost of Jupiter (NGC 3242) in Hydra (the Water Snake) and the Owl Nebula (Messier 97) in Ursa Major (the Big Bear). In late evening, the eastern sky contains the Cat’s Eye Nebula in Draco (the Dragon), the Ring Nebula in Lyra (the Harp), and the Blinking Planetary in Cygnus (the Swan). For telescope-owners, high magnification is required to see structure, and an Oxygen-III filter will brighten the planetary nebula while suppressing the surrounding stars in the field of view.
Astronomy Skylights for the week of May 26th, 2019 by Chris Vaughan.
Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!