Wed, 28 Apr, 2021

‘Pink’ supermoon will light up our skies tonight

‘Pink’ supermoon will light up our skies tonight

Looking up at the sky tonight, you can expect to see a full moon making its closest approach to Earth this month in a phenomenon described as a supermoon.

In North America, the April full moon is also known as a “pink” moon.

Despite the name it actually isn’t pink in colour. According to folklore, the moon is named for the first pink flower of the season.

While the Moon will look full for the whole of tonight, the full moon happens at a specific point in time in astronomy, when the Moon is directly opposite the Sun (syzygy).

This year, the full moon occurs just after midday on April 26th in every state except Western Australia, where it falls at 11am.

12 hours later, perigee happens, where the Moon comes within 357,378 kilometres from Earth.

Because perigee happens within 24 hours of a full moon, it’s also called a “supermoon”. But astronomers prefer to call this kind of “supermoon” a perigee-syzygy moon.

Whatever name you choose to call it, you can see the Moon in all its glory from the moment it rises.

“The astronomical full moon is 12 hours away from perigee, but to the casual observer it makes no difference,” says casual astronomer Ian Musgrave.

When can I see the supermoon?

Though the Moon will look huge as it rises just above the horizon, the time to see the Moon at its closest point will be just before or after midnight, depending on your time zone.

For those in AEST time, the Moon will be its largest at 1.22am on April 28, while those in ACST and AWST can catch the phenomenon at 12.52am and 11.22pm respectively.

In reality, it can be hard to tell the difference between a supermoon, normal full moon, and mini moon with the naked eye.

“But if you are measuring the Moon in a telescope, you’ll see it get bigger as it gets higher in the sky [and] as it gets closer to actual perigee,” Dr Musgrave says.

How common are supermoons?

Surprisingly, supermoons occur pretty frequently. Last year, there were three supermoons, including a pink one.

But, the actual number of supermoons depends on how you define the term, according to astronomer Andrew Jacob of Sydney Observatory.

The term was originally coined in 1979 to describe full moons and new moons that occur when the Moon is within 90 per cent of perigee.

Some define supermoons by the 24-hour rule, while others believe a supermoon occurs when the Moon is less than 360,000 kilometres from Earth.

Under the first rule, there are two super full moons this year.

Using the second rule, there are three super full moons and two super new moons occurring this year.

The next super full moon will fall in May. Not only will it be slightly closer than the April full moon, it will also be a total lunar eclipse across Australia.

This means the Moon will actually change colour as it passes through Earth’s shadow and will be red. 

Known as a “blood moon”, the colour is caused by sunlight that is filtered and refracted as it passes through the atmosphere. 

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