Watch Quadrantid Meteors Fly and the Moon Occult Saturn – Sky & Telescope

The Quadrantids make a bright splash at the darkest time of the year. They’re also a final opportunity to “gas up” before we enter the desert of winter and its dearth of major showers. Not until the Lyrids arrive in late April does meteoric activity pick up again. Spying a brilliant meteor shooting across the sky is one of the most moving and accessible phenomena sky-watching has to offer.

The shower has an unusually brief and intense peak listed by many sources as lasting just 6 hours. But a recent study put the duration closer to ~12-14 hours. Either way, it’s a tight squeeze. Why so short? In part because the thickest part of the stream is narrow and Earth zips through it almost perpendicularly. We’re in and then we’re out.

The shower’s radiant or streaming point lies in Quadrans Muralis, a faint group of stars in northern Boötes that was once recognized as a constellation before it fell into disuse in the late 19th century. With a declination of 49° north, the radiant is nearly circumpolar from mid-northern latitudes. But it spends much of the night near or just below the northern horizon. From latitude 40° north the shower finally comes into its own starting around 2 a.m. local time and steadily improves right up till dawn. Weather permitting, I plan to watch from 4:30 to 6 a.m. local time from a lounge chair with a thick, wool blanket pulled up to my nose.

This year, maximum is expected around 15:00 UT (10 a.m. EST) under a moonless sky. If your location happens to be in darkness and the radiant is beaming down from high, you could see a spectacular show with anywhere from 60 to 200 meteors per hour. Alaska and points east will be ideally situated for the peak; those of us in the contiguous U.S. and Canada will see closer to ~25 Quads per hour. Like all showers, Quadrantids can appear anywhere in the sky but their paths all point back to the radiant.

While the peak is one of the narrowest known, the shower is active for several days on either side of maximum, so if bad weather threatens, determined meteor-watchers will still succeed in pocketing a few needles of light. In terms of speed, the Quads sit comfortably in the middle between the faster Perseids and slower Geminids with a typical entry velocity of 41 kilometers per second (92,000 mph). Like the latter, the shower produces a good number of extra-bright meteors called fireballs.

Shower members, called meteoroids, are composed of dust and rocky bits originating from 2003 EH₁, a small asteroid with a diameter between 1.5 and 3.4 kilometers. Although classified as such, the object’s orbit resembles that of a short-period comet, raising the possibility that it may be either an intermittently active comet or a dormant one. Astronomers hypothesize it ejected the dense core of the Quadrantid meteoroid stream sometime between 1700 and 1800 A.D. This would explain its sharp peak and the fact that the shower was only first recorded around the year 1835. Other comets may be related to the shower and possibly contributed to it in the distant past including Comet 1491 I observed by Chinese astronomers and the more recent 96P/Machholz.

As you’re watching the Quads, consider that each meteor flash results from a small particle slamming into the upper atmosphere at high velocity. The rapid compression of air in the meteoroid’s path — called ram pressure — heats it to a high temperature, ablating the fragment atom by atom until it’s completely vaporized. The extreme heat generated by the object’s swift passage strips electrons from the atoms of familiar gases like oxygen and nitrogen encountered along the way. When they recombine with neighboring positive ions, photons of light are released. An electron can also absorb energy and jump from a lower to higher energy level within an affected atom. Microseconds later it drops back down and emits a photon. Both processes create the short-lived streaks of light we know as meteors. A typical meteor flash measures about a meter across and extends for tens of kilometers.

Whether you’re into physics or just like the thrill (and chill!) of watching meteors while the neighbors sleep, don’t miss the Quadrantids.

Saturn goes into hiding

On the evening of January 4th around 17:30 UT (6:30 p.m. Central European Time – CET) the dark limb of the thick crescent Moon will occult the planet Saturn for observers across much of Europe, Iceland, and western Russia. Depending upon location, the planet reemerges at the bright limb minutes to more than an hour later. Although not visible from North America, astrophysicist Gianluca Masi will livestream the entire occultation for all the enjoy on his Virtual Telescope Project 2.0 site starting at 17:15 UT (12:15 p.m. EST, Jan. 4) until Saturn reappears around 18:30 UT (1:30 p.m. EST). For that matter, he’ll also be streaming the Quadrantid shower on Jan. 3rd starting at 17:00 UT.

The International Occultation Timing Association (IOTA) has set up a special page showing the occultation visibility zone along with a list of times of disappearance and reappearance for many cities. For inspiration, check out this luscious YouTube video by Jan Koet of the planet emerging from behind the Moon’s limb in May 2007.