Space

We get many sensational news stories, saying a giant asteroid will hit Earth, or will nearly miss us. Several so far this year. Many of us worry about these things. So what is the truth behind them?

Actually astronomers have this well in hand for the largest asteroids. They have found 90% of the largest asteroids likely to hit Earth. This is mainly due to Pan-STARRS, which takes a 1.4 gigapixel image of a three degrees span of the night sky several times a minute. It continues to find a new large asteroid about once a month, and will find most of the remaining 10% by the 2020s.

Is anything going to happen on September 24th? Well, the astronomers say, no. It is an ordinary day in space, nothing remarkable of note at all on that day by way of asteroid flybys.

Yes, it's true, as some news stories say, there is a distant flyby by a rather unremarkable asteroid. It is one of dozens that pass by Earth every month. It's not especially large as asteroids go. Indeed there's one more than double its size, passing closer, at a faster speed, on October 4th that nobody is interested in except perhaps a few astronomers.

Astronomers have successfully peered through the 'amniotic sac' of a star that is still forming to observe the innermost region of a burgeoning solar system for the first time.

In a research paper published today in the journal Monthly Notices of the Royal Astronomical Society, an international team of astronomers describe surprising findings in their observations of the parent star, which is called HD 100546.

Lead author Dr Ignacio Mendigutía, from the School of Physics and Astronomy at the University of Leeds, said: "Nobody has ever been able to probe this close to a star that is still forming and which also has at least one planet so close in.


This story has recently hit the news. I think it is reasonably clear he was not putting forward a serious worked out future plan for Mars. But is there any potential in the idea?

A team of researchers that has spent years searching for the earliest objects in the universe now reports the detection of what may be the most distant galaxy ever found. Adi Zitrin, a NASA Hubble Postdoctoral Scholar in Astronomy, and Richard Ellis, a professor of astrophysics at University College, London, have described evidence for a galaxy called EGS8p7 that is more than 13.2 billion years old. 

The universe itself is about 13.8 billion years old.


This is just for fun. At first sight this seems impossible - the smallest stars are heavier than the heaviest planets, and how can something heavier orbit something that is lighter? But what if you have a very dense star and very large very low density planet? And if you interpret "orbiting it" as "having barycenter (the "center of mass of the system") within the planet"?

Also, could a star sometimes be lighter than a planet, is that possible at all? I'll also describe a way that a heavier object can, in a way, "orbit" a lighter one - a way to get a heavier star move in such a way that the barycenter of the system lies within a large low density planet - can you figure out how, before I get to it?

New research predicts that Earth has more than 1,500 undiscovered minerals and that the exact mineral diversity of our planet is unique and could not be duplicated anywhere in the cosmos. Minerals form from novel combinations of elements. These combinations can be facilitated by both geological activity, including volcanoes, plate tectonics, and water-rock interactions, and biological activity, such as chemical reactions with oxygen and organic material.


Perhaps you saw the news recently about astronauts in the International Space Station eating their first home grown lettuce? It's just a beginning, but in the future, could they grow all their own food and get all their oxygen from plants?

One day, it might be possible to detect the spread of life among the stars through panspermia--a hypothetical process of life distributed throughout the Milky Way by asteroids, comets, and even spacecraft. Henry Lin and Abraham Loeb of the Harvard-Smithsonian Center for Astrophysics propose, “If future surveys detect biosignatures in the atmospheres of exoplanets,” it ought to be possible to detect the spread of life between stars even without knowing how life spread from host star to host star. That is, we probably wouldn’t be able to detect the mechanisms of panspermia such as asteroid, spacecraft, or what have you.
Science fiction movies about aliens threatening the Earth routinely ascribe them the motive of coming here to steal our resources, most often our water.

This is ill thought-out, as water is actually extremely common. Any civilization coming to our solar system in need of water (either to drink or to make rocket fuel) would be foolish to plunge all the way inwards to the Earth, from where they’d have to haul their booty back against the pull of the sun’s gravity.