In the early morning hours of Tuesday, May 6, debris from Halley's Comet will light up the sky in this year's Eta Aquarid meteor shower. Here's everything you need to know to spot as many meteors as possible.
Above: Halley's Comet, as photographed by NASA in 1986
Halley's Comet won't make another appearance in our solar system for close to fifty years, but on its last visit, in 1986, it left some pieces of itself behind. Halley's cosmic litter has been making biannual appearances in the night sky ever since – once every October in the form of the Orionid meteor shower, and again every May, as the Eta Aquarids.
But here's the thing about the Eta Aquarids: While Australians consider the Eta Aquarids to be the best meteor shower of the year, their positioning in the night sky makes them almost imperceptible to skygazers in the Northern Hemisphere. While folks at southern latitudes can expect to spot between 50 and 60 meteors per hour, those of us north of the equator will struggle to catch site of meteors emanating from the constellation Aquarius, which will be hovering just above the Eastern horizon on Tuesday morning. If you're north of 40 degrees latitude (say Chicago, or Philly), you're probably not going to see much of anything. South of that, and you're looking at between 10 and 20 meteors per hour, and maybe a few more if you're lucky. So why bother with stargazing Monday night/Tuesday morning at all? According to meteor experts, you could spot something truly remarkable: an Earthgrazer.
Skywatching expert Joe Rao explains over at SPACE.com:
For most, perhaps the best hope is perhaps catching a glimpse of a meteor emerging from the radiant that will skim the atmosphere horizontally — much like a bug skimming the side window of an automobile.
Meteor watchers call such shooting stars "earthgrazers" and they are known for spectacularly long, colorful, long-lasting trails.
"These meteors are extremely long," Robert Lunsford of the International Meteor Organization explained. "They tend to hug the horizon rather than shooting overhead where most cameras are aimed."
"Earthgrazers are rarely numerous," NASA meteor expert Bill Cooke, a member of the Space Environments team at the Marshall Space Flight Center has said. "But even if you only see a few, you're likely to remember them."
Is it worth it? We leave that to you to decide. If you live south of the equator you're in for one of the best displays of the year. If you're in a northern latitude, and you're up for it, here's your guide to spotting as many meteors as you can. Who knows – maybe you'll spot an earthgrazer.
Avoid Light Like the Plague
We're talking all kinds of light. City lights, street lights, house lights, flashlights, any lights. On Tuesday morning, the moon will be one day from First Quarter phase, which should put it below the horizon when the constellation Aquarius appear in the southeast sky. With the moon out of sight, its light shouldn't interfere with your viewing, but there's still plenty of other ways to wash out the sky or effectively blind yourself. Seriously — don't blow it by checking your indiglo watch out of habit, and DON'T LOOK AT YOUR PHONE — it's a well-known fact that backlit cellphone screens were put on this Earth to ruin meteor showers.
If you're in the country, go find a big open field. If you're in the city, get out if you can. If you can't get out, try to find a high point. (These measures can make a HUGE difference. The pictures featured above compare the night sky as seen from two points in Utah located just 75 miles apart. The difference? The bottom photo was taken in a major metropolitan area, the top photo a rural town. See more info here.) The Clear Sky Chart website has a great list of optimal viewing locations organized by state, so go check it out.
Once you're all settled in, give yourself at least 20 minutes for your eyes to fully adapt to the dark. How do you know if your eyes have adapted? A good rule of thumb says if you can see all seven of the Little Dipper's main/brightest stars you'll see plenty of meteors. If you can't spot all 7 it's not a big deal, that's just under optimal conditions.
Know When and Where to Look
The best time to direct your gaze skyward will be in the hours preceding twilight on the morning of May 6th – though the mornings of May 5th and 7th could make for good viewing, as well. Your best bet is to watch from around 3am local time onward. In other words: you'll want to stay up late, or wake up very, very early.
As for where to look, it depends on who you ask. Some people will tell you to look towards the radiant, from which the shooting stars will appear to emanate from. For the Eta Aquarids, this is near the constellation Aquarius, which, on the morning of May 6th, will appear over the southeast horizon right around 3:00 am local time (graphic via EarthSky.org).
It's important to bear in mind, however, that meteors' trails tend to be shorter the closer they are to the radiant. Your best bet is to probably just look straight up, or to face away from the moon, keeping in mind that meteors can appear anywhere in the sky.
If you'd like to join local experts, try looking for your neighborhood astronomy club, and find out whether they'll be setting up a telescope you can peek through with friends.
Clouds ruining your skygazing? Too far north to watch? Watch it live online right here, with Slooh, starting at 6:00 PT on Monday, May 5:
NASA's Marshall Space Flight Center will also be hosting a livestream of the Eta Aquarids on Monday night. Tune in here!
Bring the Right Stuff
Bring a reclining lawn chair, a blanket and some pillows — whatever you need to get comfortable and still keep your eyes on the sky.
Bringing hot chocolate and/or coffee is strongly encouraged. Don't try to stand. Standing and looking up may seem like a decent enough idea, but eventually your neck will get tired, and the second you take your eyes off the sky is invariably when the brightest meteors of the night will go blazing by — it's like a code that all meteors live by. If you absolutely HAVE to look away, make sure it's for something awesome like taking a sip of hot chocolate.
You shouldn't really need a telescope or binoculars, because you'll want to keep your eyes on as much of the night sky as possible. Bring something to snack on, but nothing you have to look at to eat. And finally, bring some good company, so you have somebody to "ooh" and "ahh" with while stargazing on this beautiful spring night.