Wednesday, 24 April 2019 23:40

Late on ANZAC night, the Moon will pass in front of Saturn

Late on ANZAC night, the Moon will pass in front of Saturn Colin Legg Photography

An occultation occurs when one astronomical body passes on front of another. Late on the evening of 25 April, the Moon will take around an hour to pass in front of Saturn.

One of the nice things about our Solar System is that the orbits of most bodies are generally in a common plane. The orbits of most planets, moons etc are broadly parallel to one-another. This is a clear result from the evolution of the solar system from a rotating disc of gas – everything was rotating in a semi-common plane. Bodies that 'defy' this rule have either had a close encounter with something else, or have been captured as they passed by. This is also the reason why most planets also rotate in the same direction.

Sometime ago, we wrote about the much anticipated "Transit of Venus" – a 'transit is when an apparently smaller body (in this case Venus) passes across the face of a larger body (the Sun). Alternately, an "occultation" is when a seemingly larger body passes across a smaller one. The terms "transit" and "occultation" are always in simple reference to the apparent size of the objects when viewed from Earth.

Obviously, Saturn is much larger than the Moon, but from our perspective here on Earth, the Moon is so much closer and thus seems bigger and is able to easily hide Saturn from our view for a short period.

Saturn Moon 2014

Sourced from Colin Legg Photography 

So, what are the details?

Here in Melbourne, Australia, Saturn will pass behind the moon at 10:40pm and re-appear at 11:26pm, whereas in Auckland, New Zealand, the occultation lasts a little longer, starting at 12:32am on 26 April and finishing at 1:41am. The extra time is due to the fact that in Auckland, the moon is positioned such that the line of occultation is much closer to the lunar equator.

Further details of exact times in a variety of locations may be found here. The site provides a map of those areas which will have the best view.

occultation of saturn april 2019

Also, as EarthSky shows, there is plenty to see in the evening sky with Jupiter, Saturn and Antares (the primary star in Taurus) all on show.

new zealand april24

Good viewing to all. May your skies be clear.


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