Astro Bob: See the reborn moon at dusk, Lyrid meteor shower before dawn
We have several nice viewing opportunities this week: a paper-thin crescent moon April 20 and Lyrid meteor April 22-23. Plus, you can watch a live total solar eclipse.
Rebirth. Renewal. You'll find these necessities of human happiness in the seasonal renaissance of spring, a walk under the night sky or even a good book. One of my favorite symbols of new life is the return of the crescent moon at dusk. Tender and fragile as a butterfly emerging from its chrysalis, the arc of lunar light almost trembles in the twilight glow.
Most of us notice the crescent moon when it's around two days old — two days past new moon phase. At new phase the moon lies in nearly the same direction as the sun, so it's lost in the solar glare. There's nothing to see anyway because the side facing Earth is completely in darkness. As the moon moves up and away from the sun, the crescent comes into view. Hugging the horizon at first, it soon becomes obvious as it waxes, brightens and climbs up the western sky.
On Thursday night, April 20, we have the opportunity to see a much younger moon than normal. New phase occurs early that morning. By the time the sun sets, the moon will have age just 21 hours for Midwestern skywatchers (20 hours for the Eastern time zone, 22 hours for the Mountain states and 23 hours for the West Coast).
Only about 0.8% of the moon will be illuminated by the sun, so we're talking r-e-a-l-l-y thin. It will also be low in the sky — only about 5°-6° above the horizon shortly after sunset. Naturally, you'll need to observe from a place that has a great view to the west-northwest or at least a notch of unobstructed sky in that direction.
Find your sunset time at timeanddate.com/sun and start watching about 20 minutes after sundown. You'll need binoculars at first because the moon has to compete with the bright glow of twilight. Focus them on Venus, which will stand about halfway up in the western sky, and then slowly sweep back and forth about a fist above the western horizon to locate the moon. It may take a couple of tries so hang in there.
As the sky darkens the moon should become easier to see, but don't wait too long — its sets about an hour after sunset. Once you corral the crescent in binoculars try to see it with just your eyes. Although the moon will be about three fists to the lower right of Venus, a stargazing app such as SkySafari , Stellarium or Sky View makes it easy to know exactly where to look.
Once you fire up the app and check to make sure it's set for the current time, it will show the moon's position in relation to your local horizon. Hold the phone at arm's length in front of your face and move it from side to side until the moon icon appears directly ahead. Then use binoculars to search that area.
As you examine the moon you'll notice gaps or breaks along its edge. These "missing pieces" are shadows cast by mountains and crater walls that darken portions of its circumference. Yes, that's how wafer-thin this moon will be! I know it will be a challenge, but given clear skies I'm confident you'll spot it. I hope the sight inspires you to become a young crescent hunter.
See a total solar eclipse — online
Prior to the moon's return to the evening sky, it undergoes a rare annular-total, or hybrid, eclipse. Depending on where you are within the moon's shadow path you'll either see the sun as a narrow ring around the moon or completely covered in total eclipse. Earth's curvature combined with the altitude of the sun-moon combo at your viewing location gives rise to this unique scenario.
The path of totality passes over the Indian Ocean, touches the western coast of Australia and then sweeps across Indonesia and Papua New Guinea. While only a small fraction of humanity will see the eclipse in person many more can watch it online. Timeanddate will livestream the event starting at 8:30 p.m. CDT on Wednesday, April 19. Head over early and click the notification button to get a reminder.
Likin' me some Lyrids
Every April the Earth buzzes through the debris left in the path of Comet Thatcher, and we have the pleasure of watching the Lyrid meteor shower. Dust and small fragments of rock and ice released by the comet during its visits to the inner solar system strike the atmosphere at more than 100,000 miles an hour (46 kilometers per second). Although tiny, these objects carry enormous energy in the form of motion, what's known as kinetic energy.
The sudden encounter with the air at this speed slows and heats the particle, stripping it apart atom by atom until it's vaporized. At the same time, the fragment absolutely hammers the air molecules encountered along its path. They heat up and shed electrons. When the electrons rejoin the atoms moments later, energy is released, and that's what we see as a meteor. The bright streak is a mix of the vaporizing rock particle and ionized air that forms a trail several miles long and several feet (1 meter) wide.
At maximum, the shower produces about 15 meteors an hour — not a lot but enough to hold your interest. Give it at least an hour.
The best time to watch is when the radiant point, located near the constellation Lyra (hence Lyrids), stands high in the sky. That happens after midnight April 22-23, making the hours from 1 a.m. local time until dawn April 23, the peak viewing time. The shower will be active the night before and after in case you run into clouds. More good news. The moon sets well before the Lyrids kick into gear.
Grab a reclining chair, face south and enjoy the show. Remember that the number of meteors you'll see will depend on how dark the sky is. If you're in a heavily light-polluted area consider a drive to the country. Good luck and clear skies!