The week-long Eta Aquarid meteor shower reaches maximum on Saturday morning (May 6). Since the Moon is a few days past First Quarter, it will set at around 4:00 a.m., leaving only about an hour of reasonably dark sky for early morning observations of shooting stars before the increasingly bright dawn twilight becomes too restrictive.
Because these meteors appear to radiate from a position low on the eastern horizon for mid-northern latitudes, watchers in the tropics are best placed. Under the most favorable conditions a dozen or more meteors per hour can be seen from the Eta Aquarid swarm. Observers in mid-northern latitudes may only see half as many.
“So,” you might ask, “What’s the point of getting up before dawn to watch?” The answer is you might still see something spectacular!
For most, perhaps the best hope is perhaps catching a glimpse of a meteor emerging from the radiant that will skim the atmosphere horizontally — much like a bug skimming the side window of an automobile. Meteor watchers call such shooting stars “Earthgrazers.” They leave colorful, long-lasting trails.
“These meteors are extremely long,” says Robert Lunsford, of the International Meteor Organization. “They tend to hug the horizon rather than shooting overhead where most cameras are aimed.”
“Earthgrazers are rarely numerous,” cautions Bill Cooke, a member of the Space Environments team at the Marshall Space Flight Center. “But even if you only see a few, you’re likely to remember them.”
If you do catch sight of one early these next few mornings, keep in mind that you’ll likely be seeing the incandescent streak produced by material which originated from the nucleus of Halley’s Comet. The last time this famous comet swept through the inner solar system was in 1986, but it has traveled around the Sun countless numbers of times over the centuries, each time leaving in its wake trails of dust and grit similar in consistency and texture to cigar ash or copier toner – debris that astronomers believe might date back nearly five billion years to the birth of the solar system; primordial material which happens to intersect the orbit of Earth about this time in early May every year.
When these tiny bits of comet collide with Earth, friction with our atmosphere raises them to white heat and produces the effect popularly referred to as “shooting stars.”
So it is that the shooting stars that we have come to call the Eta Aquarids are really an encounter with the traces of a famous visitor from the depths of space and from the dawn of creation.