Occultation of Venus on Saturday afternoon 11th September

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mdg (September 09, 2010, 08:38:41 AM):
From the Johannesburg Planetarium......

Venus and the Moon

On Saturday the Moon will pass directly between southern Africa and Venus.

Residents of southern Africa will see:

Venus during the day

Venus disappearing behind the Moon - an "occultation of Venus" - and later re-appearing on the other side of the Moon

a spectacular early-evening sight: the young crescent Moon just above a brilliantly bright Venus (the "evening star").


It is not necessary to use binoculars or a telescope to view this - and if you accidentally aim at the Sun, you will blind yourself.

However, the temptation to view a crescent Venus near a crescent Moon is great, so if you do take out the telescope during the day, then please make very sure that there is no chance of anyone looking through it at the Sun - the only safe way to do this is to set up the scope in the shade of a building (not a tree!) and making sure it stays in the shade.

Keep the binoculars inside for the occultation - they're not necessary, they're not good enough to see a crescent, and you can't stop the kids taking them into the sunlight.

Looking for Venus

Venus is often (especially now) bright enough to see during the day. But:

* it's difficult to locate in the sky, and

* it's difficult to get your eyes to focus on it.

When the Moon is near Venus, it's easier to find and to focus your eyes on Venus.

Looking for Venus and the Moon on Saturday

The Moon will be three days old - a thin crescent, and a challenge to locate.

Look for it early morning - rising in the east from about 9am (eastern SA) or 10am (western SA). At this time, Venus will be on the dark side (east) of the Moon, about four Moon-widths below and a bit to the right of the Moon.

As the day progresses, the Sun and Moon will move across the sky towards the west (due to the rotation of the Earth); the Moon will be about 40 degrees (twice the size of your outstretched spread-out hand) to the east of the Sun. As the day goes by, the Moon will move noticeably towards Venus. Some time during the afternoon (depending on where you live in SA), the Moon will pass directly in front of Venus, hiding it - this is an "occultation".

The occultation will last from a few minutes (for Musina, on the edge of the "occultation path") up to nearly an hour and a half (for Cape Town, nearer the centre of the path).

By evening the Moon will have passed Venus; after the Sun has set, the crescent will be clearly visible for a couple of hours, just above Venus (Venus is the very bright "evening star"). This will be a beautiful sight, and if you have a small telescope, get it out and see if you can see the crescent shape of Venus - it needs a bit of magnification.

Another tip: while looking for Venus during the day, stand in the edge of the shade of a building - this will help you to avoid accidentally looking at the Sun.

Times of the occultation

This depends on where you are:

* Musina: 3:02 pm to 3:15 pm

* Jhb: 2:37pm to 3:41pm

* Durban: 2:43 pm to 3:57pm

* Cape Town: 2:15 pm to 3:41pm

For other towns, see this list

For a photo of a similar sight in 2007, see Astronomy Picture of the Day of 20 June, 2007

bluegray (September 09, 2010, 09:03:11 AM):
Cool, hope I remember to look on Saturday - might be cloudy though >:(
Mefiante (September 09, 2010, 09:48:23 AM):
Given the date (9/11 in US-ese) and the mystical connotations associated with a period of nine years, astrologers are bound to make several varieties of mind-bendingly daffy straw from this event – some strange retroactive prognostication that not only reflects the past but also heralds vague and fuzzy things about the future. IIRC, Venus symbolises love and serenity in the astrological canon, so there is no end to the amount of woo-woo its eclipsing can potentially produce…

Tweefo (September 11, 2010, 17:24:19 PM):
Typical, I've been looking forward at this for weeks and this is the first cloudy day of spring. :(
Sentinel (September 11, 2010, 20:29:22 PM):
Just came back from the Durban Day Concert with many bands including Just Jinger and Prime Circle.

This afternoon, one of the lead singers said "Hey! Look at the moon - what is that?". The Moon and Venus was behind us, so he was looking straight at it.

Later, whilst singing the song "What he means", Ard Matthews from Just Jinger (Or Jinjer as it is now spelled) asked the crowd to sing along with the chorus...

Peace, Love, more tolerance.
Faith, hope, trust in the same name of God in whose
name we die for, take an innocent life for
well that's not what he means..
and it doesn't matter what Book you read

... and added: "Even if you sing it to that Moon." :)

What a great day!


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