The latest in Ph-word: December 2020

This was easily the month that I liked the most in terms of Ph-news in the past year. When talking about space exploration, sometimes one gets the impression that all the action happened in the ’60s, ’70, maybe barely ’80s. It’s true that the topic lost its hotness when governments decided that it should; but do we realize how much we’ve progressed till then?

December served in proving this. It was all about stuff that we got from space, one way or another.

And let’s look at them right away, ranked from the nearest to the most distant.


Moon: The spacecraft Chang’e 5, by the National Space Administration of China, went to the moon, took a couple of kilograms of soil and rocks, and brought it back to earth.

The whole mission lasted three weeks and made China the third country that takes lunar samples, 44 whole years after the last such mission. In addition to its own value, the sample was selected to be two billion years younger than the previous ones. Which will permit better understanding of the aging of the bodies in the solar system.


Asteroids: Hayabusa-2, a spacecraft by the japanese space agency JAXA, brought soil and rocks from the asteroid Ryugu back to earth.

This is the first time that humans can put their hands on materials from an asteroid! (With the exception of the earlier Hayabusa mission, which brought back only a really tiny amount. Now Hayabusa-2 brought a tenth of a gram.) The geological composition of asteroids doesn’t change with time as much as planets’, so this is a chance to learn more about the early days of the solar system.

The craft left in 2014, arrived at Ryugu in ’18 and spent one and a half year in its vicinity before returning. To be precise, Hayabusa-2 didn’t bring the samples itself, but dropped them off to earth inside a capsule. It then changed its course and is now off again to meet with another asteroid.


Proxima Centauri and beyond: The Parkes Observatory in Australia caught a radio signal that looks like it is of extraterrestrial origin. I’m saying this calmly.

The signal was received in spring ’19, during observations for the privately funded Breakthrough Listen search for extraterrestrial intelligence, but was spotted in the data only last October. It has the marks of coming from a technological source rather than from natural processes.

Now, in such cases (and there’ve been such cases) the researchers start looking for all kinds of human activity that could give off a similar signal. This time, so far they can’t find any. In addition, this signal ticks several of the “extraterrestrial source” boxes. A very dramatic one is that it was registered three individual times, when the telescope was pointing at a particular spot in the sky, and disappeared when it was looking elsewhere.

And if all this wasn’t crazy enough, that particular spot in the sky happens to include Proxima Centauri, the star closest to the sun, which also has a few earth-like planets.

To spell it out, the probability that the signal actually comes from an extraterrestrial civilization is extremely small; the probability that this civilization is next door is unimaginably small. Everyone is simply waiting for the actual human-made source to be found. The story will probably turn out to be nothing.

But, as I put it in the post with the year’s top Ph-news, if it doesn’t then it’s the news of the century.


Milky Way: Keeping moving more deeply in space with each news item… ESA’s orbital telescope Gaia released its new round of data. And this led to the most detailed map of our galaxy to date.

Gaia observed each of almost two billion stars multiple times. This way it doesn’t know only their positions with fantastic precision, but also their motion, both in the past and the future.

The previous Gaia data have already led to many discoveries and it is expected to keep at it. The new round is already used for some spectacular stuff – like proving that the Milky Way grew larger during its lifetime as new stars were born. Or, finding that the solar system moves about a hundred kilometres per year with respect to none other than the universe itself (as told by observing extremely distant galaxies).


Other galaxies: And, speaking of them, the Australian Square Kilometre Array Pathfinder telescope or ASKAP, run by the australian science agency CSIRO, mapped three million galaxies.

ASKAP has a characteristically wide field of view that leads to panoramic pictures of the skies. The “survey” of galaxies, which include one million newly observed ones, was done in just 300 hours of operation.

Now, one of my personal favourite quotes about the night sky is Vincent Van Gogh’s “Looking at the stars always makes me dream, as simply as I dream over the black dots representing towns and villages on a map. Why, I ask myself, shouldn’t the shining dots of the sky be as accessible as the black dots on the map of France?”.

But this just got updated by the press release from ASKAP: the survey, it says, “is like a Google map of the Universe where most of the millions of star-like points on the map are distant galaxies – about a million of which we’ve never seen before”. Classy, ASKAP.

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