by William J. Bechaver
The Eta Aquariid Meteor Shower is at its peak this week. And though this shower is usually considered a southern shower, it promises to be better than usual this year.
Last month, the promise of the Lyrid Meteor Shower was disrupted by the brilliance of the full Moon. While usually offering about twenty meteors an hour, most were obscured by the glare of the Moon.
This month, though the Aquariids are traditionally hard to catch, this year’s display is predicted to peak on the night just following the new Moon, which means the entire shower will have virtually no interference from the Moon’s light.
So, though the radiant lies low in the south east in the early morning hours, there is still a better chance to catch more bright meteors this week.
The radiant is the point in the sky from which all the meteors seem to radiate. Usually, the higher in the sky the radiant, the better your chance of seeing more meteors per hour. With the radiant low, we’ll only have the opportunity to see about half of all the meteors that strike the atmosphere, since about that many will be below the horizon from our point of view in the northern hemisphere.
Even so, seeing only half will give us a greater opportunity for a decent show due to the lack of interfering moonlight during the peak morning. The chances of seeing great meteors are even better than they were last month, with between thirty to forty impacting above the radiant every hour.
A meteor shower occurs when the Earth passes through particles left in space by a passing comet. When a comet passes through the inner solar system, it leaves icy particles in its wake. When the Earth passes through the debris field left behind, the particles impact on our upper atmosphere, burning up as they enter. Those are the meteors we observe.
The particles can be left in space for many years. The particles responsible for the Eta Aquariids were left behind by Halley’s Comet, the most famous of comets. The last time the comet passed by was back in 1986, so the meteors we see every year are from particles left in space over thirty years ago, which are the remnants of Halley’s Comet, burning up as they enter the atmosphere.
The debris field left behind by Comet Halley is relatively spread out, so the shower can be seen for several days. Go out every morning this week and look to the south east.
The radiant is in the constellation Aquarius, which is low in the south east. Also, since the point of origin is so low in the sky, it is expected that many of the meteors we see here will have long, brilliant trails, some remaining visible for many seconds after the meteor has burned up.
So, go out and take advantage of the dark skies in the early morning hours. Aquarius rises at about 2:30, so will climb higher before the sky begins to lighten. The peak morning will be on Monday 6 May, but the meteor impacts will be visible several days in advance, and throughout the week. So this is the opportune time to view the Aquariids with the darkest of skies.
We haven’t taken note of Mars recently. And the red planet is about to be lost to the evening Sun as it lies on the far side of the solar system. We are almost as far from Mars as we can be, right now, with the Sun between us.
The last best chance to see Mars comes this week as well, as the fine crescent Moon will join it in the early evening sky. If you go out on the evening of Tuesday 7 May, just after sunset, and look to the west, find the thin crescent Moon just above the sky’s glow. To the right of the moon, about three degrees, you will be able to spot faint Mars, fading into the twilight, and the distance of the solar system.
So, though the month’s meteor shower is usually not as noteworthy, this year May promises to begin with a decent shower, and a last view of Mars to end the day.
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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.