The biggest, brightest full moon of 2014 rises this Sunday. That's exciting in and of itself (though not nearly as exciting as some headlines would suggest), but Sunday's "supermoon" also happens to coincide with the Perseid meteor shower, one of the largest and most dependable meteor displays of the year.
First things first: What makes Sunday's supermoon so super, exactly?
- As of 2:10 p.m. EDT, Sunday's moon will officially be completely full.
- The moon's fullness will coincide with its closest approach of Earth for the month, an event astronomers refer to as "perigee."
- Some month's perigees are closer than others. This month's will be the closest to Earth in all of 2014, making this month's moon especially super.
- Lots and lots of media coverage.
The fact that the moon's orbit is not circular but elliptical means that its distance from Earth varies over the course of each month. On its closest approach of our planet, the moon is said to be at perigee. When it's far away, it's at apogee. The effects of the moon's orbit on its apparent size can be seen in the animation featured at the top of this post. See how the moon appears to come out at you, only to recede back into the screen? That's perigee and apogee, respectively. The rocking motion that you see is something that astronomers call libration. It, too, has is a result of the moon's elliptical orbit.
All of these means that Sunday's moon will technically appear bigger and brighter than at any other point in the year. But unless you're comparing photographs like the one below, you probably won't actually be able to tell the difference with your naked eye. As NASA explained in the lead-up to 2011's supermoon (the largest supermoon in close to two decades): "there are no rulers floating in the sky to measure lunar diameters. Hanging high overhead with no reference points to provide a sense of scale, one full Moon can seem much like any other."
In brief: if it weren't for people telling you that Sunday's moon would be special, you might not have noticed at all. Be don't let that keep you from gazing skyward come Sunday. After all, the supermoon isn't the only thing worth looking out for that night; there's also:
The Perseid meteor shower is one of the most prolific meteor displays of the year. In 2014, activity is expected to peak in the (very) early morning hours of August 11th, 12th and 13th.
A 2010 Perseid tears through the night sky above the VLT | Photo Credit: ESO/S. Guisard
The good news about the timing of this year's Perseids is that those of us checking out the supermoon late Sunday night/early Monday morning will have a chance to watch a meteor shower, too. The bad news is that full moons have a bit of a reputation for ruining meteor showers. The light of the moon blasts your retinas, making it difficult to see all but the brightest meteors. Fortunately, the Perseids are famously luminous. According to SpaceWeather.com, observers have reported dozens of Perseid fireballs cutting through the moon's glare over the last several nights. That the meteors are holding their own, even in the days preceding peak activity, bodes well for Sunday sky-gazers.
With all that in mind, here are some tips for spotting as many meteors as possible in the nights ahead.
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.
Taking all these things into account can make a world of difference when it comes to visibility. The images featured here help illustrate the effect that light pollution can have on your stargazing experience. The bottom photo was taken in Orem, Utah, a major metropolitan area with around 400,000 people. The top photo was taken in Leamington, a rural Utah town, about 75 miles southwest of Orem, with a population of just 217 people. The difference is staggering. Give it a little forethought, and you can vastly improve your experience; 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 the stars in the Little Dipper you'll see plenty of meteors. If you can't spot them all it's not a big deal, that's just under optimal conditions.
The best hours for catching the Perseids will fall between midnight and dawn on the mornings of August 11th and 12th and 13th. That said, dozens of fireballs have been spotted over the last several nights, and more will likely be visible in the days to come.
As for where to look, that depends on who you ask. Some people will tell you to look towards the radiant, where the shooting stars will appear to emanate from (for the Perseids, this is near the constellation Perseus), but bear in mind 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. And if there's no local club, you can always join NASA's live, online chat about the shower.
Bring a reclining lawn chair, a blanket, some pillows, a coat in case it gets chilly — whatever you need to get comfortable and still keep your eyes on the sky. 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.
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 summer night.