And Slaters Go Plop

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.

The 4th to last star is the reddish one in Orion’s shoulder. If you were to fly in a fast 747 around the earth without stopping it would take something like 40 hours. If you were to do the same trip around the final star in this animation it would take about 1300 years.