Rare Planetary Lunar Occultation (PLO) in December

Those of you who follow popular science news in the papers may be aware that a few years ago Mars was remarkably close to the earth in a once in a lifetime event.

Here's an e-mail explaining it from back then:

*Two moons on 27 August*

27th Aug the Whole World is waiting for...*

Planet Mars will be the brightest in the night sky starting August.

It will look as large as the full moon to the naked eye. This will cultivate on Aug. 27 when Mars comes within 34.65M miles of earth. Be sure to watch the sky on Aug. 27 12:30 am. It will look like the earth has 2 moons. The next time Mars may come this close is in 2287.

Share this with your friends as NO ONE ALIVE TODAY will ever see it again.

I slept through it - but fortunately we have an even rarer event coming up later this year. Mars won't be quite as close as last time, but this time it will be in line with the moon!

Come 12:30 UTC on the 10th of December the red disc of Mars (first with its hazy atmosphere) will begin to obscure the bright disc of the moon. At 14:30 UTC it will be fully obscuring the moon and we'll be able to see the red disc of Mars without interfering bright moonlight!

So, break out the blankets and spend a night out under the Australian sky for this phenomenal event!

EDIT: On Tidal Forces

A work colleague asked about how this will affect tides.

Yes, it will be a monster tide - the alignment is coincidentally happening very close to the full moon. The Sun will be almost opposite the Moon but the tide will not an unmitigated disaster as you might think. Our Moon is a relatively huge satellite when compared to the Earth, and Mars' radius is about the same as the diameter of the Moon.

Mars is passing in through the orbit of the moon only briefly and its tidal forces are inversely proportional to its distance from the earth. As the tidal effect of Mars won't have time to move water very far there won't be time for the "tidal swell" of Mars to sync up with the swell caused by the Moon.

What we will see is a slight increase in the high tide and second smaller high tide (around half an hour after the normal tide in Australia).

We are made of star stuff

Today (sort of, time being relative n'all), the 9th of November, is the birthday of a great man.

Carl Sagan - born in Brooklyn in 1934 - was an astronomer, author, educator, dreamer and science advocate. He chaired the panel that created the gold records that have flown, with Voyager, past the heliopause. He persuaded NASA to turn around Voyager for one last look at Earth from six billion kilometres. He studied Nuclear Winter and the conditions on Venus. And, more than anyone else, he kindled the love of science.

In 1980 PBS released Cosmos - a personal journey discovering the universe with science. I'm not sure when exactly I saw it - but I think it was on an old black and white TV (that's right kids - they didn't always come in colour 3D) in the back room of our old rental house in outback New South Wales. Each Sunday I'd wait eagerly for the next episode and marvel at the wonders of space and the Earth. Tonight I took a break from my hardcore podcast catchup to watch the first episode of Cosmos again. There was Carl, fluffy and amiable in his turtleneck sweater explaining how Eratosthenes calculated the circumference of the world in 200BCE. Video interlacing and fuzziness on the big screen TV didn't detract from Carl sharing his love of science, knowledge and astronomy.

Cosmos is a story of wonder and loss, of the discovery of the circumference of the Earth and tragedies such as the destruction of the Great Library of Alexandria. There are moments when the simple animations almost bring me to tears, and past times when my daughter would cry "I don't want the Earth to end up like Venus". That's the secret of being a great science advocate, bring the wonder and mystery of the universe to the unknowing (but hopefully not willfully ignorant) inhabitants of this pale blue dot. Carl was my science advocate. I hope his legacy lives on.

We are made of star stuff. We are a way for the universe to understand itself. 
- Carl Sagan (1934-1996)

Cage Match - Gluten vs Holy Communion

I passed a local church yesterday and was quite surprised to see a their huge motivational board proudly proclaiming "ALLERGY / GLUTEN FREE COMMUNION BREAD".

That got me thinking... a dangerous activity while driving. If communion magically transforms communion nibbles into the actual body of a Christ, wouldn't it be gluten free anyway. Today Google/Wikipedia sucked me down and into the rabbit hole that's the swirling vortex of Christian dogma. If I'm going to have my brain explode into confused lumps I want to share - so here we are.

What we have here is the Catholic tradition of the Eucharist, followed to varying degrees in other Christian sects. The wafer and wine are blessed and undergo Transubstantiation - transforming into the body and blood of Jesus. It turns out that it's not as simple as the communion wafer actually turning into the physical body of Christ. I mean, you can test that sort of thing. The wafers would go all floppy - unless it's Jesus jerky. Instead the underlying "reality" of the nibbles is changed.

This is an new meaning to reality that I'd mercifully been unaware of. The doctrine of transubstantiation reaches back to Aristotle idea of "substance" and "accidents" - that characteristics of a thing don't necessarily define it. A chair can be made of wood or metal and might have any of a variety of shapes - so if no particular quality need be there then there must be an innate "chair-ness" that's independent of the "accidental" physical characteristics. In Catholic doctrine the idea is that the transsubstantiated body and blood don't actually have any of the physical qualities we'd associate necessarily associated with human flesh... but let's not linger on this because it makes my brain hurt.

The wafers still have gluten in them, the wine is still alcoholic. It turns out that the digestive system doesn't pay a lot of heed to the "reality" of the "substance" and people suffering from Coeliac disease still have trouble with the gluten in wafers and people with adverse reactions to alcohol still going all odd coloured.

In the Cage Match I'm putting that down as a win for Gluten and with Eucharist hiding in the happy place of the invisible reality of Jesus jerky.

Many churches are now using wholely gluten free communion bread and non-alcoholic, child friendly, grape juice. The thinking in the less dogmatic end of Christendom is that it's all alegorical anyway - why not use wafers that won't kill a percentage of the congregation?

The Catholic Church is sticking to the old format "host". In communication from the Congregation for the Doctrine of the Faith (better known under the old common term the "Holy Inquisition") reaffirmed in 2003 that the communion wafer must be made only of wheat and must have gluten.

Joseph Cardinal Ratzinger, now Pope Benedict XVI, wrote:
A. The use of gluten-free hosts and mustum
1. Hosts that are completely gluten-free are invalid matter for the celebration of the Eucharist.
2. Low-gluten hosts (partially gluten-free) are valid matter, provided they contain a sufficient amount of gluten to obtain the confection of bread without the addition of foreign materials and without the use of procedures that would alter the nature of bread.

Honestly, that seems to be kicking Coeliac sufferers when they're down.

Luckily technology marches on. Some clever religious types have sourced low-gluten flours and even come up with a low-gluten bread made with gelatinized wheat starch that's only 0.01% gluten - quite safe for most coeliacs. Sounds like a good idea to me - but still not as sensible as just not getting into the Cage Match at all.

So, for any Coeliac suffering Catholics out there there's the Catholic Celiac Society (silly American spelling :) ) but I think looking up your local bunch of reality  friendly atheists would be a better move. And by reality I mean the one that's actually measurable.