And Slaters Go Plop

Like me, you probably wonder from time to time whether you can eat the moon.

I have some bad news; you can’t, even with your friends helping you. Let’s do the figures:

The moon is bigger than it looks (this is because it’s far away) and it weighs in at about 73,477,000,000,000,000,000,000 kg. Contrary to popular opinion it’s made of rock, not cheese (and a half moon is not, in fact, half the size). The fact that it is made of rock is a spanner in the works because it considerably reduces the amount a person can eat in a day. If you want to eat it you are going to have to powder the rock first and then eat it along with other food.

Still, this is a fairly simple equation and we have all the numbers: the weight of the moon divided by the amount you can eat per day gives you how many days it will take to eat the moon.

So, let’s assume that you can eat two powdered tablespoons per meal and we’ll assume that two tablespoons of powdered rock weighs a tidy 50 grams. That leaves us with the weight of the moon divided by 0.150 kg which tells us that it’ll take a person 1,342,045,662,100,456,621,004 years to eat the moon.

If you were to enlist the rest of the world to help you in this enterprise you would be looking at reducing this figure down to a mere 203,271,750,023 years. The age of the universe is 13,700,000,000 years which means you and the rest of the world would be required to exist for 15 times longer than the entire universe has done to date. And to make things worse you’ll probably spend a considerable percentage of this time on the toilet.

(There’s no way to wrap this up in a dignified manner so I’ll just say that perhaps, one day, someone will enter the search string “can you eat the moon?” into Google and I’ll have a little chortle to myself when I see that particular stat in my logs.)

As most of us know, Jesus was bodily resurrected about 2000 years ago. After he was resurrected he ascended up into heaven. But where did he go? Did he wait until everyone had gone home and then came back down again? Did he continue on out into space to an undisclosed location? We just don’t know.

What we can know however, is the vicinity in which he must be. Even travelling at the speed of light (~300,000km per second) he’s still somewhere in our galaxy:

(Obviously, these images are of galaxies other than our own but they’re of a similar size and type. Our galaxy is about 100,000 light years across and we’re located out on one of the spiral arms.)

Carl Sagan died eleven years ago today. His enthusiasm for the universe and everything in it was contagious and he is responsible for the sense of awe I and many, many others feel when we look up at the stars at night.

Our brains are not capable of comprehending the true vastness of space but Carl managed to help us expand our comprehension to the point of vertigo and, with it, and closer understanding of our true standing within the universe.

My thoughts are with his family and I, like many others, wish he was still here.

Oh, and a few years ago I thought it would be cool if there were another habitable planet directly opposite us on the other side of the sun. It could be a similar size and distance from the sun as the earth.

Don’t you just hate that? A month or so ago I had an of idea for a sci-fi storyline but today, as I was continuing my massive 100-hour catchup of all the Skeptic’s Guide to the Universe podcast episodes, I discover that people have already been thinking about it for some time. This kind of thing happens to me a lot and I’m beginning to wonder if I’m inadvertently reading or hearing of ideas that I promptly forget and later “come up with”.

Anyway, I still think it’s a great concept for a story:

I was thinking about how impossible it is to travel to other potentially habitable solar systems (as you do) and considering how absolutely vulnerable we would be if we were to detect a super-large asteroid approaching us. We don’t have the technology yet to safely freeze ourselves for a long-haul flight through space. We don’t know how to produce food in space to sustain a group of people for any length of time. If a sizeable asteroid were to hit we’d have next to no chance of surviving the weeks or months following the impact regardless of where we were located on the planet.

I got to thinking about how we are able to freeze embryos indefinitely and figured that if we had a year or two’s notice of impending doom it might be possible to scramble together as much technology as possible to create thousands of identical small pods containing frozen embryos and fire them in all different directions out into space. I wasn’t sure whether it would be feasible to have the pods contain artificial ‘wombs’ and the materials for a biosphere that are activated upon contact with an alien planet.

Perhaps nurturing humans from frozen embryos is the most feasible option we have at our disposal for human survival across journeys that would take millions of years.

This basic premise gives you a lot of room to play with the psychology of children bought up without human parents, the sheer enormity of discovering that their biological parents have been dead for millions of years, the challenges of seeding life in a new environment, the mechanics of a life support system capable of ‘growing’ and supporting infants, the possibility of regaining contact with other pods.

It would be quite fun to be drawn along with the story only knowing as much as the children know about how they got there and what happened to earth.

Unfortunately I don’t have the skills or inclination to go ahead and turn this into a story but I implore anyone reading this who is a writer of sci-fi to take this concept and turn it into a novel. And please tell me about it! I’d love to read it.

Last week the Phoenix Mars Mission was launched and it’s out there somewhere right now travelling at 16,000 miles per hour and will reach Mars on May 25, 2008 where it will rummage around on the northern icy plains. This video is from the previous Odyssey launch in 2001.

If you haven’t read Pale Blue Dot I thoroughly recommend it.

In a nutshell: point your listening devices toward the centre of the galaxy and listen for coordinates of other intelligent civilisations.

Our solar system is in an arm of our galaxy which contains something like 500,000,000,000 stars of which we can see about 3,000 with the naked eye. When we look toward the centre of the galaxy on a clear night because we are in amongst it we see a strip of glowing haze we call the Milky Way which is in fact a lot of stars very far away all merged together.

Statistically, there is a good chance that other life has evolved in our own galaxy. In fact from what astronomers have found in the way of Earth-like planets orbiting nearby stars it looks like there is a very good chance that there are many other civilisations more advanced than our own.

SETI (at least according to Carl Sagan’s 1994 book, Pale Blue Dot) scans the sky listening for radio signals on a frequency they have assumed other intelligent life would also choose to broadcast on. Something to do with the hydrogen line. Anyway, they’ve got a lot of sky to cover and the combination of limited resources, assumptions of alien technologies and narrow frequencies they’re not having a lot of luck. The most intriguing encounters they’ve had (at least up until 1994) have all been from the direction of the centre of the galaxy. They weren’t able to pick up the signal again and it’s possible that it may have been temporarily amplified by a gravitational field or whatnot. Either way it didn’t count.

If you make the assumption that there are many, many intelligent civilisations then I would suggest that it would be a good starting place to point your listening devices toward the centre of the galaxy for the following reasons:

• It’s the one benchmark we will all know of
• If someone broadcasts a strong signal toward the centre then someone on the opposite side is likely to pick it up
• All each civilisation needs to do is broadcast a list of coordinates of all known civilisations and when a new one comes on board they append their coordinates to the list
• You then point your listening devices and transmitters at the other coordinates in the list

Now, keep in mind that I know next to nothing about sending radio signals through space (other than the fact that it takes many thousands of years travelling at the speed of light to even reach the centre) but if, in fact, it is possible to broadcast across these distances then it’s possible someone else may have had the same idea and we may pick up some handy information broadcast 60,000 years ago.

It’s entirely possible too that civilisations more advanced than us may have discovered faster ways of conveying information than radio waves (yes, yes, I know, nothing beats the speed of light) and would consider it an absurdity to revert back to the equivalent of carrying a letter by hand halfway around the world.

Here’s a photo I took of Jupiter and three of her moons. Until yesterday night I wasn’t even aware you could see the moons of any other planet without an observatory-sized telescope.

Equipment required:

• 1 x crappy telescope
• 1 x el cheepo digital camera
• 1 x hour of fiddling with settings and a tripod

I’m reading Pale Blue Dot by Carl Sagan at the moment. I’d heard of the Kuiper Belt and the Oort Cloud before but thought they were small clusters of rocks somewhere in between the planets.

No so.

The Kuiper Belt is a collection of big rocks ranging from a kilometer in size up to Pluto (yep, Pluto is now part of that collection) which is 2320km across and others that are even larger. It’s in a disc shape starting at Neptune and extending for about 3 billion kms (20AUs) and Neptune, which is the furthest out of our planets, every once in a while manages to pull one of these objects out of its orbit around the sun and occasionally flings it inwards causing much of the pock-marking we see on the moon and other planets. Including Earth. Neptune is throwing rocks at us.

The Oort Cloud extends beyond the Kuiper Belt, is in the shape of a sphere rather than a disc, extends a long way out (the Kuiper Belt extends to 50AUs and the Oort Cloud as far as 100,000AUs). All of these objects are held in orbit by the force of the Sun’s gravity.

To get an idea of the size of our solar system take a look at the ongoing travels of Voyager 2. It was launched in 1977, sling-shotted around Juipter in 1979, did the same to Saturn, Uranus and Neptune in 1981, 1986 and 1989 respectively and continued on outwards travelling at a speed of 3.3AUs per year (55,000km/h).

Travelling at 55,000km/h it’ll take something like 20,000 years to clear our solar system. If it were heading toward the nearest star to us it would take about 80,000 years to get there.

Let’s face it, unless we invent a snappier way to travel we’re going to have a long term plan for this planet we live on.