The Moon and why did it look so big this week

[kipper]

Interesting article on why the moon looked so big.

http://news.bbc.co.uk/2/hi/uk_news/magazine/4619063.stm

[Gordon]

Interesting article on why the moon looked so big.

http://news.bbc.co.uk/2/hi/uk_news/magazine/4619063.stm

There is a problem or 3 with that article, they fail to mention why it looks larger than usual; the reason is that the perigee point of the moon's orbit (closest to Earth) was within a day of Full Moon. There's one Full moon per lunar month and also one perigee, but they only occasionally coincide, since they have slightly different periods. People tend to notice the Full Moon more than other phases, because it is brighter then, plus conveniently located near the horizon just after sunset, people rarely look up much above the ground. Some people dont know the moon can easily be seen in the daylight sky!

Also, they fail to mention the reason behind this statement:
"Not since June 1987 has the moon been this low in the sky, accentuating the illusion even further"

This has to do with the moon being nearly as far south of the ecliptic as it can be, near Full Moon. However, when it is rising, it is as low as it can be!, and that happens every day of the year. What they fail to explain is that from the northern parts of the Northern Hemisphere the moon doesn't get as high above the horizon at its highest point (culmination) as it does on average. However, this also means that for typical Southern hemisphere viewers at 30deg South, the Moon is higher in the sky than usual at culmination. The Moon illusion only occurs when it is quite near the horizon, so the moon being so far south at Full Moon doesn't really have a huge effect on the illusion, unless you are quite a long way north, and it lessens the effect for southern observers, since it rises more quickly for them.

Personally I tend to favour the flattened dome perception of the sky explanation, the Ponzo Illusion theory cant be correct, since the moon is not placed within converging lines, but above any that exist, and the illusion is still apparent even when no foreground objects are visible, such as over a featureless plain or the ocean.
Photography shows the moon is no larger when its on the horizon, merely distorted out of shape by the greater thickness of atmosphere near the horizon.

Gordon

[Killakoala]

I agree with Gordon.

Who'd trust the BBC anyway, when we have an astronomer in our midst!

(I had a perigee once, but it flew away) BTW Gordon, did you get any photos of the Moon/Jupiter occult the other day?

[Gordon]

 BTW Gordon, did you get any photos of the Moon/Jupiter occult the other day?

It was cloudy when they were closest in the afternoon, and still lots of cloud around later when it got dark. I did have a look through gaps in the clouds, but didnt bother taking a pic, since I have similar pics on slide, and it was unpleasantly cold and windy outside!

Gordon

[Killakoala]

Fair enough. I was in Townsville when it happened but i did manage to see it through some 25x binoculars. Unfortunately i too was unable to take a photo of it due to being extremely busy working at the best viewing times. Such is life.......

[leek]

Steve,

Not sure if this is what you meant by occult, but did you see the one I took?

[Killakoala]

Steve,

Not sure if this is what you meant by occult, but did you see the one I took?

That's the one. An occult is when one object passes behind another one, such as jupiter passing behind the moon.

[Gordon]

Steve,

Not sure if this is what you meant by occult, but did you see the one I took?

That's the one. An occult is when one object passes behind another one, such as jupiter passing behind the moon.

Generally referred to as an "occultation"

To occult means to cover

here the sky is occulted by fog and cloud

Gordon

[cyanide]

Wow - that is fascinating, Gordon.

Do you have any links for websites that talk about this, and specifically, that predict such occurrances? Also things like comet passings, eclipses etc etc? I am guessing that a lot if not all of these events are predictable down to the day...?

[Gordon]

Wow - that is fascinating, Gordon.

Do you have any links for websites that talk about this, and specifically, that predict such occurrances? Also things like comet passings, eclipses etc etc? I am guessing that a lot if not all of these events are predictable down to the day...?

Generally predictable to the second The Astronomical Society of NSW has an annual Ephemeris for sale that tells you when they are happening.
Available at some bookshops and all astronomical stores.
In the evenings at the moment Saturn, Venus and Mercury are all rather close together in whats known as a conjunction.
A good place to look for info about comets is the Comet Observation Home page, although it assumes you already have some knowledge of the terminology. Of course theres always my page for comet pics

Gordon
http://www.ozemail.com.au/~loomberah

[leek]

Wow - that is fascinating, Gordon.

Do you have any links for websites that talk about this, and specifically, that predict such occurrances? Also things like comet passings, eclipses etc etc? I am guessing that a lot if not all of these events are predictable down to the day...?

Try http://www.heavens-above.com

You can programme in your location and it will give you lists and reminders of significant events and where to look for them...
Check out the Iridium flares...

[Gordon]

spaceweather.com is another good place to look, they generally have info about current events such as occultations and conjunctions.

heavens-above.com is about the best web site around for producing lists of satellite passes for any location, HST, ISS, Shuttle etc.

Gordon

[cyanide]

Excellent links - many thanks, guys!!