For those not averse to spending some early morning hours away from city lights under the stars, the early part of May might surprise with a pre-winter spectacle. At the time of writing, we are in the building phase of the Eta Aquarids meteor shower.
Meteor showers occur at well-defined times during the year, lasting from a few days to several weeks.
Meteors, often called shooting stars, have nothing to do with stars at all. They start out as meteoroids which are essentially tiny ‘crumbs’ left behind by comets or, on occasion, asteroids. These fragments continue to orbit the Sun, following the paths of their parent bodies. If those orbital paths happen to intersect with Earth’s orbit, Earth passes through those crumbs every year. The ones that strike Earth’s atmosphere are called ‘meteors,’ appearing as bright streaks in the sky, as they burn up due to air friction at high altitudes. Very rarely, larger fragments don’t fully burn up, and impact the ground, becoming known as ‘meteorites’.
Showers are best observed in the early hours of the morning from about 1 or 2 a.m. through until dawn. This is because as Earth orbits the Sun, its ‘leading’ side, or bow if you think of Earth as a ship, is the morning side – i.e.: from 12am to 12pm. Imagine Earth ploughing through a field of space dust with the bow collecting most of it and the stern seeing only a few, and you’ll get the idea.
The annual Eta-Aquarid shower begins about April 20th and lasts for five weeks or so. Unlike most meteor showers, there is no sharp peak for the Eta Aquarids. Instead, a plateau of good rates can be enjoyed for about a week. This year the peak centres around May 5th/6th happily coinciding with the new moon, potentially making for excellent dark sky viewing.
The crumbs that create this shower originate from the most famous of all comets, comet Halley. This shower’s meteors are also known for their speed. Striking Earth’s atmosphere at 66 km/s they sometimes leave glowing trains in their wakes.
Showers seem to emanate from particular directions in the sky unique to themselves. The direction is known as a shower’s radiant. The Eta Aquarids get their name from their radiant which is in the constellation of Aquarius (the water bearer), quite close to one of its brightest stars, Eta Aquarii. This star is one of the four that make up the top of the ‘water jar’. Remember that meteors do not appear at their radiant, unless they are heading straight for you (what are the chances?), usually they appear tens of degrees from it.
Globally, the Eta Aquarids are one of the most active showers, peaking at around 60 meteors per hour. If the constellation Aquarius was at our zenith (overhead), and we could observe the whole sky at once, we might observe 60 meteors in an hour. It is never directly overhead from our latitudes but is still well placed for observation. In the hours just before dawn, it will be rising quite high between east and northeast. The further north you are, the better. Still, wherever you are in New Zealand, this shower may be well worthwhile pursuing!
If possible, get to a place where city lights won’t spoil your viewing, carry a blanket or a comfortable chair, along with some healthy dollops of patience. Be sure to check the weather! Clouds and rain will definitely spoil your night ☹. Round up some friends and you’ll not only make it a fun sociable experience, but you’ll also maximise the amount of sky being observed. Please let us know how it goes. We’d love to learn about your experiences from different parts of the country.
John Rowe, Astronomy Educator
This link will take you to the useful Time and Date website where you can select your location, time, and date to help you make the best of your viewing experience.
Find out more in-depth information here.
The ever-changing night sky is a fascinating vista best appreciated by patient and prepared eyes. By subscribing to our monthly ‘Space News’ you’ll have access to our Sky Spotter column, which if read in conjunction with our Star Charts or a night sky app, will help you learn seasonal highlights of the night sky, spot the Moon, planets, and spectacular conjunctions.