by William J. Bechaver
Though generally considered an average meteor shower, there is more to the springtime Lyrid shower than meets the eye.
In the past, we have examined the origin of meteor showers. Most major predictable showers are caused when the Earth passes through the debris field left behind by a passing comet.
In the case of the Lyrid meteors, the responsible visitor is Comet Thatcher, a relatively long-period comet which last passed and was identified way back in 1861.
Comet Thatcher orbits the Sun only once every 415 years, so the particles left behind from its tail at that last passing, over a hundred and fifty years ago, are responsible for the Lyrid meteors we see every year.
Once a year, the Earth’s orbit takes us through that cloud of remaining icy particles. When they impact on the upper level of our atmosphere, they burn up, streaking across the sky in the remarkable fireballs we witness every year.
But in addition to the peak activity we see every year, there are also periodic outbursts of greater activity that have been reported through the ages.
The earliest reports of one such outburst come down to us from way back in 687 B.C. So by that, we know that Comet Thatcher has been orbiting the Sun for millennia.
The last recorded outburst was back in 1982, which rivaled the one reported in 1922. With additional data from the recorded increases in activity, astronomers now predict that they occur in cycles of every twelve years, with some being more intense than others.
This can be attributed to the grouping of the particles left behind, which seem to be effected by the passing of the other planets in the solar system, and the gravitational effects of not only the Earth, but also of other larger bodies, like Jupiter and Saturn.
So, taken into consideration, this year could be the year of such an outburst of activity, with Earth passing through a more dense area of the debris field.
There was a time in 1982 when an incredible 250 meteors were recorded in a one-hour period. Incredibly, that’s between four and five meteor strikes every minute! So it will be worth it to take a look this year, for a chance to witness a spectacularly rare display.
This year, the Lyrid Meteor Shower will peak before dawn on Sunday 22 April. They seem to radiate out from the constellation Lyra, the harp, from which we derive their name.
The brightest star in the region is Vega, which rises before ten o’clock at night. As it climbs higher in the east on peak night, the first quarter Moon is rapidly sinking in the west.
By the time the radiant near Vega has reached its apex, almost directly overhead, the Moon will have set, leaving the sky perfectly dark for meteor watching.
The early morning hours of Sunday will be the best time, with typically 15 to 20 meteors per hour, or one every three to four minutes.
However, remember, meteors are unpredictable and irregular. You may see several all at once, then go several minutes without seeing any.
Or, if we’re lucky, perhaps we will be treated to one of the rare, cyclical bursts that only appear every twelve years.
Whatever the case, with the Moon absent from the early morning sky, it will be a perfect opportunity to go out and catch the best spring meteor shower, and perhaps, in the process, witness a display which is truly rare and historical.
Remember, meteor showers increase over a span of days. The Lyrids actually began earlier this week, and some scientists are predicting a second period of peak activity on the morning of Tuesday 24 April, before they taper off by the end of the week. I suggest getting an early start on viewing, a few days ahead of time. And if the weather interferes on Saturday night and Sunday morning, try going out the next couple of mornings to catch a glimpse of the best spring shower we’re likely to have this year!
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• · William J. Bechaver is the director of SPACE • Spanish Peaks Amateur Cosmos Enthusiasts, the premier Astronomical Society for Southern Colorado and Northern New Mexico.