The two richest, most reliable meteor showers — the Perseids and Geminids — will be free of moonlight this year.
Of all the celestial sights visible during the year, meteor showers seem to captivate public interest more than most — and it's easy to understand why. On a quiet, dark night under the stars, it's rather transcendent to see a bit of space rock create the sudden dash of a shooting star as it tears into the top of Earth's atmosphere, ending its life in a moment before your eyes after ages in space. Moreover, annual meteor showers are fairly predictable, coming at about the same times each year.
But like much else in amateur astronomy, meteor observing goes best with patience and foreknowledge.
What Are Meteors?
A meteor is the streak of light you see when a bit of interplanetary debris vaporizes white-hot as it rips into Earth's upper atmosphere at a speed of 30 to 70 km per second (20 to 45 miles per second). And although some meteors look so bright you could almost touch them, actually they occur very high up, at altitudes of 80 to 120 km (50 to 75 miles).
Meteors are common. If you gaze steadily into a dark, moonless night sky somewhere far from city lights, you'll likely see a sporadic (random) meteor a few times an hour throughout the year. But showers bring the main action.
Meteors range in brightness from tiny blips just at the limit of visibility to dramatically bright fireballs that outshine Venus and maybe even light up the landscape around you. The rarest of these, called a bolide, shatters explosively into pieces during its rapid descent and, if it penetrates deep enough into the atmosphere, can create a boom or rumble that reaches you a minute or two later. Those are once in a lifetime events.
Because they arrive so fast, even small meteor particles produce a lot of light. Typically they're no bigger than large sand grains. Something the size of a pea can create a meteor that's dramatically bright. Those high velocities give each little particle a lot of kinetic energy, which converts to heat and light due to friction and shock heating in the upper atmosphere. Many people think a meteor occurs because the particle "burns up." But actually, as the particle vaporizes, the shock wave spreading away from it heats air molecules to thousands of degrees. The air molecules usually cool in a split second, giving off light as they do. (The in-depth explanation.)
What Is a Meteor Shower?
Most meteor particles (they're called meteoroids when they're still in space) are bits of debris that were shed by comet nuclei crumbling when warmed by the Sun. The debris continues along the comet's orbit, eventually spreading all around the orbit and out to the sides as well. Whenever Earth, in its own orbit, passes through one of these sparse streams of grit, the result is a meteor shower. Many sporadic meteors, on the other hand, are rockier debris from old asteroid collisions.
During the half dozen strongest annual showers, under a dark sky you may see something like 10 to 60 meteors or more per hour late at night. Some showers mostly come and go in a few hours; others last for weeks.
Keep watch for at least a half hour during one of the stronger showers, and you'll notice something: Not only are meteors more frequent than usual, they appear to fly in directions away from a particular point in the sky. That point is called the shower's radiant. It's the perspective point where all the shower members (which are flying in parallel) would appear to come from if you could see them approaching from far away in space, instead of in just the last second or so as they enter the atmosphere. They can appear anywhere in your sky. But their paths, if you trace them backward far enough, all intersect the radiant spot.
To get a better sense of the picture, check out the interactive meteor-stream animations created by Ian Webster. The one below shows particles spread out around the orbit of Comet 109P/Swift-Tuttle, the comet responsible for the Perseid shower. (Have some fun with it: Click and drag the animation to get different perspectives, or go to meteorshowers.org to try a different shower.)
(Note: Most of the actual meteor streams are somewhat narrower than displayed; the animations are based on meteor directions and speeds measured from the ground, and slight measurement errors broaden the 3D paths shown in space.)
Meteor Shower Radiants
A shower usually gets its name not from its parent object but from the constellation where the radiant lies. For example, August's well-known Perseid shower has its radiant in Perseus, and December's Geminids appear to radiate from Gemini. One notable exception is the Quadrantid shower, named for the now-defunct constellation Quadrans Muralis. Its radiant is in northern Boötes.
The higher a shower’s radiant appears in your sky, the more nearly straight down the meteoroids arrive, and thus the more you'll see in a given area of sky. When the radiant is low, we see few. When the radiant is below your horizon, none of the shower members appear at all.
Meteor showers are usually at their best after midnight, because most radiants are highest in the hours before dawn. The graphic below shows why: Morning is when you're on the side of Earth facing forward along Earth's orbit. We circle the Sun at about 30 km (20 miles) per second, so interplanetary debris slams into the morning sky especially fast, making each meteor brighter than it would be if it had hit in the evening, when it would be catching up to Earth from behind.
Think of raindrops hitting your car's windshield. If the car is moving forward, the drops hit harder and more plentifully. In addition, the radiant of the raindrops shifts to somewhat in front of you. You can see this in your headlights on a rainy or snowy night.
Solar-system dynamicists have gotten rather good at predicting when a particular shower might display an extra burst of activity. Usually these bursts, typically lasting just a few hours, are from thin, denser"ribbons" of particles embedded in the larger stream — particles that were ejected by the parent comet only decades or centuries ago and have not had time to disperse much. And some meteoroid streams have a higher proportion of large particles than others, which create more fireballs.
The table and descriptions below list the year's best and most dependable annual displays. (There are many more: The International Astronomical Union now recognizes more than 100 well-defined meteor showers and hundreds of other "shower candidates" that remain unconfirmed. But most are so weak that it takes trained and very patient observers, or nowadays automated cameras, to detect the pattern.)
How to Watch Meteor Showers
Find a dark location with an open view overhead as far from urban light pollution as you can get, and where no local lights glare into your eyes. Find a way to block any lights you can't escape and the Moon, too, if it's up; you want your best night vision so you can see more meteors. Your night vision improves for at least your first 30 to 45 minutes in the dark.
Make yourself comfortable in a reclining chair, and wear more warm clothing than you imagine you'll need. When you're exposed to a wide expanse of clear sky, radiational cooling will chill you to a surprising degree even in summer. Especially if you're out in the coldest hours of the late night, and aren't moving!
A sleeping bag provides warmth and mosquito protection. Put DEET repellent on your exposed parts if it might be buggy. Lie back, gaze into the darkest part of your sky (usually straight up), contemplate the stars, and be patient.
Meteor Showers in 2023
The dates in the table below are for the predawn hours in North America closest to the predicted peak of Earth's passage through the meteoroid stream. Many showers are also active for several nights before and after the peak date.
Important: The listed hourly rates are what a viewer would see under ideal conditions: a very dark sky free of moonlight or light pollution (stars of magnitude 6.5 detectable naked-eye), with full dark adaptation and the radiant high overhead. Rarely are we so blessed, so most likely you'll see lower rates than those listed.
|Major Meteor Showers in 2023|
|Shower||Radiant (and its rough direction)||Morning of maximum||Peak hourly rate||Parent comet or asteroid|
|Quadrantids*||Boötes (NE)||Jan. 4||40-120||2003 EH1|
|Lyrids||Lyra (E)||April 23||10-20+||Thatcher (1861 I)|
|Eta Aquariids*||Aquarius (E)||May 6||20-40||1P/Halley|
|Delta Aquariids*||Aquarius (S)||July 30||20||96P/Machholz|
|Perseids||Perseus (NE)||Aug. 13||90||109P/Swift-Tuttle|
|Orionids||Orion (SE)||Oct. 22||10-20||1P/Halley|
|Southern Taurids||Taurus (overhead)||Nov. 5||5-10||2P/Encke|
|Leonids||Leo (E)||Nov. 18||10-20||55P/Tempel-Tuttle|
|Geminids||Gemini (E)||Dec. 13, 14||100||3200 Phaethon|
|Ursids*||Ursa Minor (N)||Dec. 23||10||8P/Tuttle|
Bold type indicates the best predicted showers this year.
* Strong moonlight will interfere with asterisksed showers.
January 4: The Quadrantids
In some years the "Quads" deliver at least 1 or 2 meteors visible per minute under excellent sky conditions — if everything aligns just right. In fact, the nominal zenithal hourly rate (the ZHR: seen by someone under a perfectly dark sky when the shower's radiant is overhead) is a very high 120 — in some years it's been 200!
But few observers ever see anything close to that many Quads, because the shower's peak lasts just a few hours. That brief period is likely to miss your good meteor-watching hours depending on what side of the globe you live on. In 2023 the timing is good for Europe: around 3:00 or 4:00 Universal Time January 4th. But alas, the light of a nearly full Moon will wash the sky.
The parent of this shower is a small object designated 2003 EH1 for its discovery year (now it's also known as asteroid 196256). It loops around the Sun every 5½ years between the orbits of Earth and Jupiter. In 2004 meteor specialist Peter Jenniskens discovered that this body is responsible for the Quadrantids. It's not an active comet — more likely it's an "extinct comet" that no longer has any ice to evaporate.
April 22: The Lyrids
More than 3½ months pass until the next major annual shower. April’s Lyrids are usually weak; you might glimpse one every 5 minutes. But surprises occur; counts exceeded one a minute during a Lyrid outburst in 1982. The predicted peak this year (near 1h UT) is best for Europe. The thin waxing crescent Moon will not be an issue. Any Lyrids you see will emanate from a radiant at the Hercules-Lyra border, near the bright star Vega.
May 6: The Eta Aquariids
This annual shower originates from none other than Halley's Comet, and its meteors come in fast: 66 km (41 miles) per second! This blazing speed often creates trains — something like incandescent smoke trails — that linger for several seconds after the meteors themselves have come and gone. However, the shower's radiant (in the Water Jar asterism of Aquarius) stays low before dawn as seen from mid-northern latitudes, so rates for us are low. For the Southern Hemisphere this is often the best shower of the year. But in 2023, the pre-dawn sky will be lit by a brilliant full Moon.
July 30: The Delta Aquariids
This long-lasting shower, more formally called the Southern Delta Aquariids, has a radiant below the celestial equator and thus, like the Eta Aquariids, is best seen from the Southern Hemisphere. Take the nominal peak date here with a grain of salt; the shower is at least slightly active all the way from mid-July to mid-August. For us northerners, its radiant well above the southern horizon for a couple of hours before to a few hours after midnight.
August 12: The Perseids
Even casual skywatchers know about the Perseid shower because it often delivers an average of a meteor per minute, under pleasant summer skies during vacation season when more people than usual are under unspoiled rural darkness.
This year we're in luck. For North Americans the Perseid maximum comes at just the right time, spanning our early-morning meteor-watching hours when the radiant is highest. The Moon is a thin waning crescent and out of the picture. Make your plans!
You'll catch some Perseids in the evening too, just not as many; the later you watch the better. On the other hand, the Perseid radiant (near the Double Cluster in Perseus just under Cassiopeia) clears the northeastern horizon by roughly 8 p.m. When the radiant is low, the few Perseids you see will be dramatically long, skimming almost horizontally far across the top of Earth's atmosphere.
The Perseids are bits of debris shed by Comet 109P/Swift-Tuttle, which orbits the Sun every 130 years. Careful observers first realized that the Perseids are an annual event in the 1830s.
October 22: The Orionids
Here's another modest shower due to Halley's Comet; Earth makes two passages through Halley's meteoroid stream in our annual circle around the Sun. Like the Eta Aquariids, this shower lasts for several nights running. The first-quarter Moon sets by about midnight on the night of October 21-22, leaving the morning hours dark. The Moon sets a little more than an hour later each night after that. The radiant (in Orion's dim club, above orange Betelgeuse) will be highest in the hour before the beginning of dawn.
When at their very best, such as 2006–09, the Orionids boasted peak rates of more than 50 meteors per hour. Since then the activity has dwindled to less than half that.
October 12–15: The Southern Taurids
November 5: The Northern Taurids
Don't take those dates too literally. The broad, weak, combined Taurid display sputters along from the beginning of October through mid- to late November. It typically produces at most a dozen meteors per hour around its poorly-defined maximum. Moreover, while both components include bits of debris shed by Comet 2P/Encke, a recent analysis shows that a host of other objects — near-Earth asteroids, collisional fragments, and dormant cometary nuclei — might be creating several overlapping streams of particles. Consequently, both Taurid components have broad maxima that aren’t easy to pin down.
The Taurids are also known for a high proportion of bright fireballs — occasionally, an extremely bright one that makes the news.
The Taurids strike the atmosphere at a relatively slow 19 miles (30 km) per second. They are catching up with Earth from behind, which means that unlike the case with most showers, they're most numerous in the evening.
November 17: The Leonids
The Leonid shower's parent comet, 55P/Tempel-Tuttle, tends to leave narrow, concentrated streams of debris. These produced prodigious displays in the late 1990s, when the comet itself last swung through the inner solar system. Since then the shower's activity has greatly declined, usually offering just a slight trickle radiating from Leo’s Sickle in the hours before dawn. Moonlight will not be an issue.
December 13 and 14: The Geminids
This shower in frigid nights is usually the year’s best and most reliable, with upward of 100 meteors per hour radiating from a spot near Castor in Gemini. The radiant is well up in the sky by 9 or 10 p.m. as seen from mid-northern latitudes and is highest overhead around 2 a.m. A waxing crescent Moon this year sets early and poses no problem.
We list two peak mornings to watch this year because for North Americans, the shower's fairly brief maximum falls between them. It's predicted for about 19h UT December 14th, which is 2 in the afternoon on that date Eastern Standard Time.
Geminid meteors come from 3200 Phaethon, an asteroid discovered as recently as 1983 that circles the Sun every 3.3 years. In fact, Phaethon might be considered a "rock comet" that sheds bits when its rocky surface heats up to roughly 1,300°F (700°C) at perihelion, blazingly close to the Sun.
December 23: The Ursids
Although the Ursid shower delivers only a modest 10 meteors per hour even under the best conditions, it has the advantage of a radiant near the bowl of the Little Dipper in the north — so it's up all night for skywatchers at northern latitudes. Peak activity, which lasts just a few hours, is predicted for around 4h UT on the 23rd. That's 11 p.m. on the 22nd EST, well timed for eastern North America and especially western Europe. But this year there's a bright waxing gibbous Moon. The Moon set about 1½ hours before dawn begins, offering that short window of darkness.
PS: Did I mention that meteor observing requires patience? Kind of like the rest of amateur astronomy? In the Sunday newspaper comics after last year's Geminids, there appeared this Arlo and Janice strip.