How to see the 2017 Perseid meteor shower
Your guide to catching a glimpse of the Perseid meteors, coming to skies across the northern hemisphere from July 17 to August 24.
What is a meteor shower?
A meteor shower occurs when a cloud of debris from a comet or asteroid enters Earth’s atmosphere and burns up, leaving bright trails. Most often these debris particles are not much bigger than grains of sand.
In space anything up to about a metre in diameter is technically termed a meteoroid; when a meteoroid hits the Earth’s atmosphere, it becomes a meteor. A group of meteors is a meteor shower.
Because the particles are all moving in the same direction, to an observer on the ground they appear to radiate from a single point in the sky.
What are the Perseid meteors?
The Perseid meteors are meteoroids ejected from Comet 109/Swift-Tuttle, which orbits the the Sun every 133 years. The comet has left behind debris all along its orbital path. Every year at about the same time, Earth’s orbit crosses that orbit, leading to one of the most famous and ‘fiery’ meteor showers.
The Perseids are known for producing long arcs of light and colour so intense they are called ‘fireballs’. At the peak of the shower there can be 150 or more visible meteors an hour.
Where and when to look
The Perseid meteor shower will be visible from July 17 to August 24, with its peak on August 12 or 13. There will be good view from anywhere in the northern hemisphere; viewers close to the equator in the southern hemisphere may also see a few meteors low on the horizon.
The best time to look for meteors is between midnight and dawn, when the sky is dark and the radiant of the meteors is reasonably high.
The radiant of the Perseid shower is in the constellation Perseus, hence the name. Perseus rises in the north-east in the early evening and will be high in the sky, a little to the east, shortly before dawn.
For best viewing, wait for a clear night and get out of town. The less ambient light pollution, the more meteors you will see. In 2017, the moon will be three-quarters full around the peak meteor time for the Perseids, so try to find a spot that also blocks the moonlight.
The other thing to remember is that star-gazing is a waiting game. Bring a picnic blanket and be patient.