Category Archives: Astronomy

More junk than space

During 3CR’s Radiothon week (it’s not too late – donate now), I was asked a question by our colleagues from Spoken Word: how much space junk is there?

Thanks for asking! And the answer, unsurprisingly, is a lot.

Plot of space debris being tracked in Earth orbit by NASA
Plot of the roughly 22,000 pieces of space junk large enough to track (> 10 cm). The outer ring is the very useful geostationary orbit, at an altitude of 35,786 km. But the vast majority of objects are in the dense white region further in - this is low Earth orbit, between 160 and 2000 km altitude. (Image by NASA)
Let me be more specific. Like, millions, or even tens of millions of pieces.

Continue reading More junk than space


Help, our mass is missing

The universe is not what you think it is. We look out into space and imagine it’s full of worlds like ours, but most of what’s out there is completely different and entirely baffling.

First, the obvious. Those lights you see in the night sky are mostly stars – billions and billions of stars. Our galaxy alone contains about 300 billion of them, and with an estimate of more than 170 billion galaxies in the universe, that makes the total number over 50×1021. That’s 50 followed by 21 zeroes, which is an exceptionally big number.

Hubble Ultra Deep Field image of more than 10,000 galaxies in a tiny patch of sky (click to embiggen - it's worth it)
Hubble Ultra Deep Field image, taken in 2004, showing more than 10,000 galaxies looking back about 13 billion years in time, all within a patch of sky less than 1/10 the diameter of the full Moon and that looks empty when seen from Earth (Image: NASA)

The point here is that they far outweigh any planets that may be out there. In our solar system, all the planets, dwarf planets (hello Pluto!), asteroids, comets, etc. make up only about 0.14% of the mass – the remaining 99.86% is the Sun.

But although stars are pretty much all we can see, there’s plenty more out there that we can’t see. And recently, two separate teams of Australian researchers have shed some light on what this missing mass may be. Continue reading Help, our mass is missing

Citizen science

Because you’re reading this blog, I’m going to assume that you have at least a passing interest in science. But why just read about it when you can get involved!

Recently on the show, Beth told us about some research projects that ordinary, non-professional scientists can join to expand the world’s knowledge – and have a bit of fun too. Here is a list to get you started:

  • Biodiversity Snapshots is a field guide for your mobile device that helps you identify animals and then submit the place you observed them to an online database.
  • EteRNA is an online game where you come up with new combinations of RNA (ribonucleic acid, which encodes and transmits genetic information) that can then be synthesised to see how they work.
  • Foldit is a similar game where you design proteins and score points depending on how well they fold.
  • SETI@home lets you donate your computer’s unused processing power to search for extraterrestrial signals in data collected by radio telescopes; it was one of the first distributed computing projects.
  • ClimateWatch tracks changes in flowering times, breeding cycles, migration movements and other phenology to monitor the effects of climate change.
  • Field Expedition Mongolia searches 85,000 satellite photos of Mongolia to try and locate the tombs of Genghis Khan and his descendants.

Apart from these mostly online projects, you can join real world organisations, like Frog Watch, or the the Field Naturalists Club of Victoria (which we also featured on-air recently, as its members found a new shrimp in Port Phillip Bay).

Of course, these are only the tip of the iceberg. You can find more citizen science ideas at Wikipedia, of all places, or just keep your eyes, ears, and curiosity open.

Mercury may be Planet X

It could mark the spot where interplanetary pirates buried their treasure, or maybe it’s a clue to the last remaining supply of Illudium Phosdex, the shaving cream atom. But this photo released by NASA’s MESSENGER spacecraft (MErcury Surface, Space ENvironment, GEochemistry and Ranging) is awfully intriguing:

X-shaped craters on the surface of Mercury (click to embiggen)
Mysterious X-shaped craters at latitude 2.22°, longitude 216.0° E on Mercury, as seen by the MESSENGER spacecraft (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Okay, I know what you’re all thinking, and no: I don’t really want you to think it was made by aliens. Like the famous Face on Mars, this remarkable pattern appears to have entirely natural causes.

How do we know? Well, we zoom out, of course:

Long view of the region on Mercury with the X-shaped crater (click to really embiggen)
In this wider, mosaic view, Crater X can be seen slightly above and to the right of the centre. Click to view full size (NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington, thanks to the USGS)

As this larger image shows, it appears to have been formed by streams of material emitted from two other nearby impact craters (the image is taken from the United States Geological Survey’s Map-a-Planet mosaic of photos from MESSENGER and the earlier Mariner 10 spacecraft).

Of course, what it may in fact be, is an example of pareidolia, the tendency for humans to see patterns in random shapes, like animals in clouds, or Jesus in a tortilla.

But hang on a moment. The story seems to have been spread via a article, which brings up the whole ‘Face on Mars’ thing and says that “for some people, reason and logic will always take a back seat to unwavering hope”.

However, a quick click around UFO websites, the majority are just repeating NASA’s explanation, not jumping to the whole aliens-did-it conclusion.

So maybe this whole story is itself a bit of pareidolia, an attempt to find an expected conclusion in a random event. Woah, I think I just went a bit metatextual there…

Is SETI worth it?

In recent weeks, SETI, the Search for Extraterrestrial Intelligence, has been all over the news and the intertubes. This was because of the SETI Institute being forced to shut down its research at the Allen Telescope Array due to a lack of funds.

Front view of antennas of the Allen Telescope Array
Front view of antennas of the Allen Telescope Array, being built by the University of California at Berkeley, outside San Francisco. The first phase, consisting of 42 6-metre dish antennas shown here, was completed in 2007. Eventually it will have 350 antennas. (Photo by Colby Gutierrez-Kraybill, via Wikimedia Commons)
But is this shut down, or “hibernation” as they’re calling it, a good thing or a bad thing? Is SETI worth the time and effort, not to mention the funds, to keep going?

On the “nay” side, it’s extremely unlikely we’re going to hear anything. After all, we’re not talking about picking up the equivalent ordinary radio or television broadcasts: this would have to be a message deliberately beamed in our direction. So it assumes an intelligent civilisation in our nearby galactic neighbourhood (out to about 1000 light years), sending a message at just the right frequency the precise moment we’re pointing our telescopes at them.

Now, the only “intelligent civilisation” in the galaxy that we know of is, well, us. And we generally seem to agree that sending messages out into space isn’t a good idea (or at least, that’s what Stephen Hawking says). So why should we expect someone else to be doing it?

Normally when you have a scientific hypothesis that’s so theoretically unlikely, and hasn’t shown a positive result in over 50 years of experiments, then you’d say that it’s time to give up. Especially when there is so much other good science on which to spend your money and effort.

But on the other hand, the amount of money required really isn’t that much compared to other things humans spend money on. And the potential payoff if something is found is incredible: it would be one of the biggest scientific discoveries in the history of, like, ever; it’s something that couldn’t help but change our view of our place in the universe.

And, to put it simply, you’ve got to be in it to win it. As described excellently by Carl Sagan, it would be a shame if someone sent us a message and we weren’t listening.

It’s a bit like playing the lottery every week: your chances of winning are so slight, that on average you’re going to spend far more on tickets than you can expect to win. But the weekly cost is still relatively small, and the possible payout so enormous, that maybe it’s worth it. At least that’s what plenty of people seem to believe  – although I have to confess, I’m not one of them.

What do you think? Is the lottery of alien communication worth the cost? Or do we, as a civilisation, have better things to do?

Formaldehyde good for preserving ingredients of life

A while ago we looked at those lizard people from Doctor Who, and how they hid underground to avoid an impending collision with the approaching Moon, according to a 40-year-old theory about its formation.

Obviously, this is all made up. And now we know better about how the Moon was formed: it wasn’t captured into orbit at all, but instead formed from the debris of a collision with an object about the size of Mars, around 4.4 billion years ago.

But this actually raises its own dilemma of how the fragile ingredients of life – the carbon, oxygen and hydrogen that make up organic molecules – avoided being blown off into space in such a cataclysm.

Hypothetical view of a Mars-sized object hitting the Earth
A hypothetical view of a Mars-sized object hitting the Earth, resulting in a collision that would form our Moon from the debris, but undoubtedly causing a lot of damage in the process (Image by Fahad Sulehria, via Wikimedia Commons)
Well, it now seems possible that those elements were locked up in chains of formaldehyde (CH2O). Formaldehyde is, of course, very poisonous, which is why it’s good for preserving things in jars because no bacteria are going to go near it.

But it’s also capable of reacting with itself to form polymers that can survive extreme conditions – including temperatures as high as 1400 °C – which may have been the thing that prevented the precursors of life from boiling away into space.

This idea was suggested recently by George Cody, from the Carnegie Institution of Washington, and his colleagues (Cody GD, Heying E, Alexander CMO, Nittler LR, Kilcoyne ALD, Sandford SA & Stroud RM, “Establishing a molecular relationship between chondritic and cometary organic solids”, Proceedings of the National Academy of Science, published online April 4, 2011).

It was already known that formaldehyde is common in interstellar clouds, but what Cody et al. showed was that formaldehyde polymers could lead to the types of organic molecules found on comets (which have been sampled with probes) and carbonaceous chondrites, a type of meteorite. And these organic molecules are very similar to the compounds that would have been needed to kick-start life on Earth.

So, formaldehyde: quite capable of preserving the ingredients of life just like it preserves heads in jars. But it is poisonous, so be careful to keep your spaceship windows closed when you’re flying through interstellar gas clouds.

Read more about this research at Discovery News.

The methane rain falls mainly on the plain

NASA’s Cassini space probe has been orbiting Saturn (that’s the pretty planet with the rings) taking pictures of it and its moons since 2004. In particular it’s focused on Saturn’s largest moon, Titan; in fact, Cassini travelled to Saturn accompanied by a lander called Huygens, which actually went down to Titan’s surface.

Titan is so intriguing for scientists because it’s large enough to have an atmosphere. And recently Cassini was fortunate enough to catch pictures of methane rain around Titan’s equator.

Image from NASA's Cassini spacecraft, showing a huge arrow-shaped methane storm blows across the equatorial region of Saturn's largest moon, Titan (click to embiggen)
A huge arrow-shaped methane storm blows across Saturn's largest moon, Titan (Image: NASA/JPL/SSI)

Along with its parent planet, Titan is over 9 times further from the Sun than the Earth is, so naturally it’s a lot colder. Its average surface temperature is −179.5 °C, which is of course well below the freezing point of water.

But methane (chemical formula CH4), which is a gas on Earth, is liquid between -182.5 °C and -161.6 °C. This means that Titan can experience the same types of weather events – rain, storms, etc. – as us. Only with methane instead of water.

Continue reading The methane rain falls mainly on the plain

Arsenic-based lifeforms? Really?

First of all, a NASA astrobiologist, Felisa Wolfe-Simon, and her team found some bacteria in Lake Mono, in California.

Felisa Wolfe-Simon processing mud from Mono Lake to inoculate media to grow microbes on arsenic (click to embiggen)
Felisa Wolfe-Simon processing mud from Mono Lake to inoculate media to grow microbes on arsenic (Image by Henry Bortman, via NASA)

This lake has very high salinity, high alkalinity and high levels of arsenic. Dr Wolfe-Simon’s team extracted a strain of  Gammaproteobacteria, which they cultivated in a laboratory and called GFAJ-1 (short for “Give Felisa a job”).

When they cut off the bacteria’s supply of phosphorous – essential for DNA, cell membranes and other metabolic processes – it continued to grow. This led them to conclude that arsenic – which, although usually poisonous, is chemically similar to phosphorous – had taken its place.

Then NASA put out an announcement…

Continue reading Arsenic-based lifeforms? Really?

Voyage to the heliosphere

The two Voyager space probes were launched in the 1970s, and in their tour of our Solar System they greatly increased our knowledge of the outer planets (as well as taking some great photos).

They’re still going over 30 years later, and are now at the very edge of the Solar System.


Diagram of Voyager 1 and 2 leaving the heliosphere, into the heliosheath
Voyager spacecraft exiting the heliosphere (Image: NASA)

The heliosphere is a giant bubble formed by the solar wind, charged particles emitted by the sun, as it blows against the interstellar medium, made of other particles that flow between the stars.

Voyager 1 is currently believed to be in the heliosheath, the turbulent area outside the bubble of the heliosphere. NASA rocket scientists expect that in about 4 years the spacecraft will experience a sudden drop in temperature as it finally leaves the sun’s influence and drifts into interstellar space.

For more about the Voyagers and their outward journey, see the NASA Jet Propulsion Laboratory website.