Galaxies Galore, a Major May Monday Meteor Shower, and Lunar-Looking Advice!
We live inside the Milky Way. Our sun is embedded within its five thousand light-year thick disk of obscuring stars, dust, and gas. Because of this, our best opportunity to see other galaxies is to look directly up and out of the plane of the Milky Way’s disk, where there is less clutter to peer through.
At this time of year in the northern hemisphere, the Milky Way hugs the eastern horizon in the evening hours. The sky overhead, which includes the constellations of Leo (the Lion), Virgo (the Maiden), Coma Berenices (Berenice’s Hair), Canes Venatici (the Hunting Dogs), and Ursa Major (the Big Bear), is absolutely loaded with distant galaxies!
Astronomers make the effort to take out their telescopes on clear spring evenings to see and photograph the many treasures that float above us. On my Tumblr post last week, I included an image of three spring galaxies in Leo. This week, I’ll include an image taken just last night near Collinwood, Ontario of an unusual-looking spiral galaxy designated NGC 4088. It’s located 61 million light-years from our solar system. While you are looking, see how many other smaller galaxies you can see around it!
A Major Meteor Shower
The annual Eta-Aquariids Meteor Shower is produced when the Earth passes through a trail of material left by repeated passages of Halley’s Comet, and those particles drop through our atmosphere at high speeds, leaving long streaks of ionized gas and minerals. We pass through the debris from May 3 to 11 annually, and we will be most deeply in the cloud around Monday, May 6. Your best times for seeing the meteors will be Sunday and Monday, especially before dawn.
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 on the peak night, and fewer than that during the surrounding nights. 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
The next two weeks of May will be an ideal period to view our natural satellite’s rugged terrain in binoculars and backyard telescopes at a convenient time of the evening! Fresh from yesterday’s New Moon phase, the young crescent moon will appear low over the western horizon for a short time after sunset tonight (Sunday). Then, on the following evenings, the moon will set later — climbing higher while waxing fuller.
As the moon waxes, the sun is rising over its eastern horizon. East on a planet or moon is defined as the direction where the sun rises. Due to the moon’s tidal lock with Earth, the moon keeps the nearside hemisphere pointed towards Earth at all times. That means that sunrise on the moon takes hours — and the sun needs two weeks to cross the moon’s “sky” and set in the west.
On Earth, we define morning as the daylight period between sunrise and high noon — or about 6 hours. But at any given location on the moon (except the poles), that process covers the period from New Moon to First Quarter — or about a week! The rising sun casts long shadows to the west of any elevated terrain, including crater rims, mountains, boulders, and faults. Shadows on the moon are nearly black because there is no atmosphere to scatter light.
The shadows are particularly stark along the terminator, the pole-to-pole boundary line that divides the lit and dark hemispheres of the moon. Along that strip, the sunlight is nearly horizontal. Every night, and even hour-by-hour, the terminator shifts west — throwing new areas into stark relief. Keep your telescope handy and have a look on every clear night. Or, for a fun exercise, look at a feature early in the evening and look at it again a few hours later. Try holding your phone over your telescope’s eyepiece and taking a pair of photos at the two times — or draw what you see.
Let’s review what else the moon will be up to this week. Early Monday evening in the west-northwestern sky, the moon will be positioned just above the stars forming Taurus’ triangular face, and that constellation’s brightest star, Aldebaran. Use binoculars to capture the scene. Observers in Europe, Africa, and Asian will see the moon pass through Taurus’ face after dusk.
On Tuesday evening, the waxing crescent moon will land 3.5 finger widths to the lower left (south) of reddish Mars. Look for a medium-bright star named Zeta Tauri (ζ Tauri) aka Tianguan positioned close to the upper, northern tip of the moon’s crescent. That star marks the eastern horn of Taurus, the Bull.
The moon will pass through the twins of Gemini on Wednesday and Thursday. Then, on Friday the nearly first quarter moon will pass almost directly through the large open star cluster in Cancer (the Crab) known as the Beehive, Praesepe, and Messier 44. The moon will be centered on the cluster at approximately 10 pm EDT. Binoculars or a telescope at low magnification will show both the moon and the cluster at the same time. To better see the clusters’ stars, try to position the moon just outside of your optics’ field of view. (Binoculars will show the cluster to the moon’s upper left, but your telescope will flip that view around.)
On Saturday night the moon will reach a 90° angle with respect to the sun, triggering its First Quarter phase worldwide. By this time, you might have noticed the moon in the afternoon daytime sky. At First Quarter, the moon always rises at noon and sets after midnight. The moon will end the week below the stars of Leo (the Lion) next Sunday night.
Mars will continue to be 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, 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.
This week, the very bright planet Jupiter will be visible low over the southeastern horizon after midnight 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. Jupiter will reach its highest point over the southern horizon by 4 am local time and then descend towards the west as dawn arrives. Soon, 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.
Look for yellowish Saturn, which will be rising about 2 hours after Jupiter all summer, sitting about 2.5 outstretched fist diameters to the lower left (east) of Jupiter in the pre-dawn sky. Saturn will officially enter the evening sky in the last week of May. Dust off your telescope because even a small telescope will show its rings!
Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will rise a little before 4 am local time. But I’ll wait for summer, when it will be available in the evening, to look for it.
Venus tends to be easy to see because of its extreme brightness. But our sister planet is approaching the pre-dawn sun now, so you will need a wide-open eastern horizon to see it just before sunrise. Venus will rise at about 5 am local time and remain visible until about 6 am. It will soon disappear in solar conjunction.
Astronomy Skylights for the week of May 5th, 2019 by Chris Vaughan.
Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!