Old Morning Moon Leaves Dark Nights for Stars, a May Meteor Shower, and Leo Lurks in the South!
A May Meteor Shower
The annual Eta-Aquariids Meteor Shower, produced by material from Halley’s Comet, runs from April 19 to May 26 and peaks before dawn on Sunday, May 5. True Aquariids will appear to travel away from a radiant point in Aquarius (the Water-Bearer), which will sit near the southeastern horizon. The southerly radiant makes this shower better for observers at low latitudes. Watch for up to a few dozen meteors per hour, including some fireballs, near the peak. The very young evening moon will leave the sky nice and dark for this shower.
To increase your chances of seeing meteors, find a dark location with lots of sky, preferably away from light polluted skies, and just look up with your unaided eyes. Binoculars and telescopes are not useful for meteors because their fields of view are too narrow to fit the streaks of meteor light. Don’t watch the radiant. Any meteors near there will have very short trails because they are travelling towards you. Try not to look at your phone’s bright screen — it’ll ruin your night vision. And keep your eyes heavenward, even while you are chatting with companions. Happy hunting!
The Moon and Planets
This is the week of the lunar month when our natural satellite swings towards, and then past the sun, leaving our night time skies darker — perfect for stargazing!
The moon will begin this week as a waning crescent shining prettily over the eastern pre-dawn horizon. On Wednesday morning, the even slimmer crescent will begin a dance with bright Venus. That morning, the moon will sit a generous fist’s diameter to the right of the planet. Try to see them before about 6 am local time. On Thursday, the moon will land about 4 finger widths to the lower right of Venus.
From Friday morning until just after sunset on Sunday evening, the moon will be invisible, because it will be positioned near the sun in the sky. During that period, the sunlight reaching the moon will only shine on the lunar farside. New Moon phase will officially occur at 6:45 pm EDT on Saturday evening. The young crescent moon will be a little easier to spot, sitting low in the western sky, on Sunday after sunset.
As I just mentioned, Venus will be easily spotted in the eastern sky just before sunrise all this week. At the same time, the elusive planet Mercury will be positioned a bit less than a fist’s diameter to Venus’ lower left (east). Both planets will be surrounded by the dawn twilight, making much dimmer Mercury a challenge to find. Venus will rise at about 5:15 am local time. In a telescope, it will exhibit a not-quite-round disk. Both planets are swinging towards the sun and will soon disappear in solar conjunction.
Mars will continue to be easily visible for about an hour after dusk every evening this week. Even though Mars will be setting in the west just before midnight local time, the later spring sunsets mean that it’s starting to dip into the twilight. Once the sky has darkened, look for Mars as a medium-bright, reddish pinpoint of light sitting less than one-third of the way up the western sky. Mars has been slowly shrinking in size and brightness as we increase our distance from it little-by-little. The bright reddish star Aldebaran will be sitting a fist’s width below Mars this week. Don’t confuse them — Aldebaran is brighter than Mars, but Mars is a mere 18 light-minutes away while Aldebaran is 66 light-years away!
By the end of this week, the very bright planet Jupiter will begin to rise over the southeastern horizon by 11:30 pm local time. If you are walking through the house in your pj’s during the wee hours, Jupiter’s bright beacon might catch your eye through a southerly window. Until sunrise at about 6 am local time, Jupiter should remain visible over the south-southwestern horizon. In a few weeks, I’ll start to alert you to when you can see the Great Red Spot and the shadows of Jupiter’s four large moons when they cross Jupiter’s disk.
Yellowish Saturn, which will be rising about 2 hours after Jupiter all summer, will be sitting about 2.5 outstretched fist diameters to the lower left (east) of Jupiter in the sky. Saturn will officially enter the evening sky in the last week of May. Dust off your telescope! Even a small telescope can see its rings.
Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius. It will rise after about 3 am local time. But I’ll wait for summer to look for it.
The Lion Hunts
For millennia, sky-watchers have imagined the stars in the night sky linking into patterns — forming humans and animals and inanimate objects. We call these groupings constellations, after the latin for “stars grouping together”. Each culture has assigned their own spin on the heavens, usually naming the patterns after things in their everyday experience. For example, south sea islanders saw outrigger canoes, and the Inuit saw the Big Dipper as the Caribou and Cassiopeia’s “W” as the Blubber Container with a Lamp Stand nearby.
In modern-day astronomy, the entire sky is divided into 88 officially recognized constellations. The manner in which the stars are connected into stick figures is not regulated, but the boundary lines between the constellations is. That way, there are no gaps in the coverage, and every object in the heavens can be placed within one of the 88 regions. By the way, astronomy has a long tradition in China — and they connected smaller groups of stars, yielding several hundred Chinese asterisms or 星官, xīngguān.
A handful of constellations are so obvious that many independent cultures assigned the same figure to those stars. A perfect example of this is the spring constellation of Leo (the lion). The lion was identified as early as 1000 BCE by the Babylonians, and later by the Egyptians, Greeks, and Romans. To the Greeks it represented the Nemean Lion slain by Hercules during his labours. Only the beast’s own claws were sharp enough to slice its hide.
It’s easy to find and recognize this constellation, even from suburban skies. Head out on the next clear evening and face the south. Leo is a large constellation situated more than halfway up the evening sky, and just above the imaginary Ecliptic line which the Sun, Moon, and planets all move along. For this reason, Leo is one of the twelve Zodiac constellations. He is positioned with his head facing right (west) and his tail towards the left (east).
The lion’s brightest star is Regulus. Regulus means “Little King” in Latin and its Arabic name Qalb Al Asad translates to “the heart of the Lion”. A blue-white star with a visible small companion star nearby, it’s the 21st brightest star in the heavens, and it sits almost on the Ecliptic, so it is frequently occulted by the moon and the inner planets.
From Regulus, move upwards and trace out another five modest stars forming a backwards question mark, or sickle. This represents the lion’s neck, head, and mane. The second star up from Regulus is another reasonably bright star named Algieba, or “the forehead”. In a backyard telescope, Algieba splits into a very pretty pair of yellow stars, one slightly brighter than the other.
From Algieba, cast your gaze a bit more than fist’s width to the left to find a star of similar brightness named Zosma, situated at the lion’s hip. Then, angling down and to the left another fist’s width, we find a star at the lion’s tail, Denebola, the second brightest star in the constellation. Denebola is a young star only a few hundred million years old. It emits quite a bit of infrared radiation, suggesting that this young sun may have a planet-forming dust disk around it.
The last major star of Leo, named Chertan, sits to the lower right of Zosma and Denebola. The three stars form a nice triangle. This is where things get interesting! Leo is a favorite of amateur astronomers because it is located away from the plane of the Milky Way, in a direction of sky that contains a nice selection of relatively nearby and bright galaxies.
Draw a line from Zosma to Chertan and, about two finger widths farther from Chertan is found a famous set of three spiral galaxies called the Leo Triplet. All three galaxies (two of which are on Charles Messier’s list, M65 and M66), when viewed from a dark sky location, can be framed in a good telescope at low magnification. Another sprinkling of galaxies is located midway between Chertan and Regulus, two finger widths below the line joining the two stars. This group contains M95, M96, and M105 — plus another non-messier galaxy. And that’s just the beginning — the patch of sky located about a fist diameter to the rear of Denebola contains dozens of bright galaxies! But that’s another story…
For the next couple of months, Leo will slowly stalk westward across the heavens. Take a few minutes to look at this majestic and ancient constellation.
Astronomy Skylights for the week of April 28th, 2019 by Chris Vaughan.
Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!