Only the very brightest “shooting stars” will be visible during the August Perseid meteor shower expected to peak in the early hours of Saturday, as the full moon will interfere with visibility.
“The problem this year is that the moon will be full on the 12th. A bright moon interferes with the observation of any faint object,” explains astrophysicist Joseph Caruana.
Every year, come late July or early August, I start receiving countless messages from people from all walks of life asking for details about the Perseids.- Astrophysicist Joseph Caruana
“This means that, with the exception of the very brightest of Perseids, one does not expect to be able to see that many this year as they require a dark sky.”
Every August, enthusiasts look forward to the meteor showers, known locally as Id-Dmugħ ta’ San Lawrenz (tears of St Lawrence), and head to dark spots around Malta and Gozo to enjoy the spectacular site.
“The interest is incredible. Every year, come late July or early August, I start receiving countless messages from people from all walks of life asking for details about the Perseids and how best to observe them. It is delightful to see the interest they generate, especially because they can serve as a gateway for young children to start exploring astronomy and, more generally, science,” says Caruana.
What causes the meteor showers?
As he shares his enthusiasm about the subject, Caruana explains that, to understand meteor showers, it is first important to understand comets.
Comets are made of a mixture of rock, ice and dust. They generally have highly eccentric, as opposed to circular, orbits around the sun, meaning that they approach the sun from the outer regions of the Solar System.
As a comet approaches the sun, gasses are released as it heats up and this leads to a discharge of solid rock particles. In effect, through this process, the comet leaves behind a trail of debris.
If the orbit of our planet traverses this debris, the solid grains left behind by the comet end up colliding at high velocity with earth’s atmosphere.
A small grain simply vaporises and leaves a glowing trail which is called a meteor, or a shooting star, although this has nothing at all to do with stars. Larger rock fragments, on the other hand, can explode and create what is known as a fireball or bolide, Caruana explains.
Why are they visible in August?
The Perseids – which is the official name for the August meteor shower because they appear as if they are emerging from the constellation of Perseus – come around every year when earth traverses the remains that were left behind by a comet called 109P/Swift-Tuttle.
It is best to watch out for Perseids between August 11 and 13, with the peak this year predicted to occur in the early morning hours of the 13th. However, one can also catch a few of them on the days either side of this period.
Dark sites need to be preserved
Generally, the best place would be the darkest site one has access to but since this year there’s the moon, the sky will be bright anyway, says Caruana.
“It is so important to preserve the very little we have left in terms of dark sites on our islands. Our Dark Sky Heritage Areas are being neglected on account of no proper enforcement of existing policies and at the same time light pollution is on the increase.
“It can be mitigated effectively through very simple measures such as using properly designed lighting fixtures, avoiding excessive lighting and making use of timers in the case of lighting that is not required after a given hour of night (churches, public monuments, etc.).
“However, despite all efforts, in return there has only been empty talk as pledges to address the issue have not materialised. In many cases, the situation is actually becoming worse.”
We are still in time to enact positive changes that would make a difference to future generations, he adds.
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