Watching meteors is one of the simplest forms of astronomical observing. Just about anyone can enjoy meteor watching, from just about anywhere in the world. Enjoying the show takes only a couple things… A dark sky and a comfortable place from which to watch.
Meteors are simply small bits of debris hitting the Earth’s atmosphere at very high speed, typically tens of thousands miles per hour. Our solar system is rich with this debris. Most of these bits are quite small, about the size of mote of dust or a grain of sand. Something the size of a pea would create a spectacular fireball that lights up the whole sky. While they often seem close, they are actually quite high, 60 miles (100km) above the ground when they flare into short lived fireworks.
The mechanism for the show is simple. When something hits the very thin air high in our atmosphere at very high speed it compresses the air in front of it. This compression also heats the air, causing it to glow white hot. Heated enough, the air becomes a plasma, the molecules shredded and electrons freed from the atoms. It is not the meteor itself that you see, but the glowing plasma around it.
There are a number of questions many people ask about meteor observing. You can find many of the answers below. Watching a meteor shower takes no special equipment, expert knowledge or extravagant preparation. This is an activity nearly anyone can enjoy, one of the spectacles of nature available to all.
The first meteor shower of 2012 is likely to be a good one. The Quadrantids are a reliable shower, producing 60-120 ZHR, one to two meteors per minute. The Quadrantids are named for the obsolete constellation Quadrans Muralis, now part of the constellation Boötes.
For viewers in the mid-Pacific the peak will arrive early on the morning of January 4th. The radiant rises around 2am, creating a pre-dawn event. Set the alarm clocks early for this one. While the predicted peak is January 4, 07:20 UT (January 3, 21:20 HST) the show should be quite decent for hours either side of this time. Unlike other showers where activity can occur for days or even weeks, the Quadrantids have a sharp peak, activity falls off rapidly on the preceding and following nights.
The Moon is still a few days short of full, allowing several dark hours before dawn for meteor watching. Moonset will occur about the same time the radiant rises, about 2am, giving observers about three hours of good dark skies to enjoy the event.
The annual Geminid meteor shower has become one of the most reliable annual meteor showers. First observed over 150 years ago this is a interesting meteor shower. The parent body for the Geminids is not a comet, but rather the asteroid 3200 Phaethon. It is somewhat of a mystery how this mostly rocky body gives rise to the debris stream needed to generate a meteor shower.
The evening of Dec 14th into the morning of Dec 15th is favored, starting around 8pm as Gemini rises in the east.
While the 2011 Geminids are expected to just as numerous as usual, viewing will be hampered by a bright Moon in the sky. Certainly the brighter fireballs will be easily visible, but the dim meteors will be lost to the moonlight. If you do wish to try your luck, view between midnight and dawn on the night of the 14th and into the morning of December 15th. It may be possible to see some meteors after the radiant rises, about 8pm, and before moonrise around 10pm on the evening of the 14th.
For meteor watchers there is probably no more anticipated show that the annual Leonid Meteor Shower. The Leonids are renowned for reliable showings featuring bright fireballs.
The reputation is not without reason, Leonid events over the last decades have produced spectacular showers. The 2001 Leonids have become legendary, for a few brief hours on the morning of November 17th the shower became a true meteor storm, with rates of more than one thousand meteors an hour visible across the western United States and the Pacific. The sky was constantly peppered with streaks, many dim, but some very bright, every few minutes a fireball would be brilliant enough to light up the landscape. Other observers will mention that the 1998 Leonids produced a impressive number of bright fireballs, making that year particularly memorable.
Nor is the 2001 event unprecedented. This has happened in the past, with Leonid meteor storms occurring several times in the last couple centuries. In 1833 a massive shower woke residents across the eastern United States with a fury that had many thinking that Judgment Day was upon them.
The Leonid meteor storms incited terror and religious revelation, but also stimulated the study of meteor science. It is from studies of these storms that astronomers began to realize that meteor showers were natural, and predicatable phenomena. This led to the realization that the annual meteor showers were associated with comets with orbits that cross the orbit of the Earth.
Just how impressive a show depends on a set of complex factors, meteor prediction is not an exact science, but astronomers are getting steadily better at these predictions. The meteoroids are found in clouds of debris left behind by a comet. In the case of the Leonids this is comet Temple-Tuttle, which has an orbital period of 33 years. All along the orbit of the comet there is a cloud of debris, small bits of dust and sand sized grains of rock-like material. Prediction is a matter of figuring out how this material will move about under the influences of gravity from the various planets and other factors like the pressure of the solar wind and even sunlight.
Unfortunately for meteor watchers, the 2011 Leonid shower is expected to be fairly weak, with ZHR rates around 20. There are some predicted peaks, due to specific regions of debris left behind by the comet several centuries ago, but the average meteor size is predicted to be quite small, leading to to faint meteors. This is further complicated by a bright waning gibbous Moon present during the shower peak. This is probably not a good year for Leonid observing.
Thanks to all of those folks who posted comments about meteor fireballs. As I mentioned, these sort of events are not all that uncommon, and occur regularly across the globe. What is unusual is good photos of the event. This did happen this week, a photographer had a good camera at the ready when a similar fireball came in over Groningen, Netherlands on October 13th. Great photos of an event much like the one we saw last week over Hualālai. Check out his page for the full set of photos including the final breakup, the website is in Dutch, but a Google translation will let you follow the description.