11 Aug Perseids meteor shower 2015 peaks this week
The Perseids meteor shower hits its peak this Wednesday night. The annual light show will provide night owls with some one hundred “shooting stars” an hour.
Regarded as one of the more “reliable” meteor showers, the Perseids provide plenty of wonder for the amateur night sky watcher. This year, the shower will coincide with a new moon for the first time since 2007. The darker moonless sky allows more meteors to be observed. Even better the forecast is for largely cloud-free skies allowing an uninterrupted view of this spectacle.
Another important aspect of viewing in dark skies is getting away from artificial light. Homildon abuts the Northumberland International Dark Sky Park which makes for perfect viewing being Europe’s largest area of protected night sky, awarded gold tier designation by the International Dark Sky Association. If you are heading out into the dark, take a red light torch rather than a regular one to protect your night vision – you can even make your own.
Watch the Perseids
This year’s Shooting Star Spectaculars at the Kielder Observatory may be fully booked but there is no need for any special equipment to view the Perseids – just watch the sky and keep your eyes peeled. The visible rate is greatest in the hours before dawn. However although evening to midnight sees a lower rate, it also has a chance of seeing particularly bright meteors or “fireballs”.
The Perseids appear to originate from the same point in the sky, near the constellation Perseus from which they gained their name. From this “radiant”, however, they can appear to travel in any direction. Nasa advises to “look towards the familiar constellations Cassiopeia and Perseus in the north-east”.
Once you are well away from light pollution, and for the best chance of seeing the shower, lie flat on your back for a panoramic view of the night sky.
The excellent Dark Sky Diary explains that the number of meteors seen every hour depends on the density of the dust cloud hitting the atmosphere at that moment, the height above the horizon of the radiant, the darkness of your sky and how cloudy it is.
What are the Perseids?
The meteors are actually debris from Comet Swift-Tuttle, long broken away leaving a plume trailing through space. Every August the Earth’s orbit intersects this plume, causing a light show as particles of ice and dust hit the Earth’s atmosphere. Although these are tiny – from the size of a grain of sand to around as big as a pea – they are traveling at high speed, around 60km/s. At that speed, it would take less than a minute and a half to travel from Homildon to New York City! This means the air in front is compressed when the meteor hits the atmosphere, the air in front of it compresses incredibly quickly. Those who remember Boyle’s law from school will realise this results in the gas temperature rapidly rising, causing the meteor to heat up so much that it glows. The air burns the meteor until there is nothing left.
If you miss the next couple of nights, do not despair! Although the Perseids meteor shower peaks in mid-August it builds up each year from around 17 July running through to 24 August, even if only a few meteors an hour are visible as it tails off.