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.

Is the ISS the most expensive single human artefact ever, after adjusting for inflation? Well, to start with, it's a whole lot more expensive than a medieval cathedral anyway. First we need an estimate of the cost of the ISS, and this article in the Space Review estimates the total cost up to 2015 as $150 billion (in 2010 dollars). That's the total cost including all the international partners. So, how much did it cost to build a medieval cathedral?

A team of researchers has discovered a Jupiter-like planet within a young system that could provide a new understanding of how planets formed around our sun.

The new planet, called 51 Eridani b, is the first exoplanet discovered by the Gemini Planet Imager (GPI), a new instrument operated by an international collaboration headed by Bruce Macintosh, a professor of physics in the Kavli Institute at Stanford University. It is a million times fainter than its star and shows the strongest methane signature ever detected on an alien planet, which should yield additional clues as to how the planet formed.

This is just a fun question someone asked on Quora. It leads into a few interesting topics. First the ISS just isn't heavy enough for a satellite to enter into a true gravitational orbit around it. But, in theory at least, you can put a satellite into a temporary  orbit that looks from the point of view of the ISS as if it is in orbit around it.

For a while. It's not kept in place by any gravitational attraction to the ISS, so it is sort of an illusory orbit you could say in a way - but perhaps it is interesting.

We know that our universe has already lived through great number of exciting phases.

But new research released overnight shows the universe has long passed its peak and is slowly but surely dying.

The research was presented at the year’s largest gathering of astronomers at the International Astronomical Union’s General Assembly in Hawaii.

Before we start writing any obituaries, let’s have a quick recap of the good times.

Most people, when they think about exploring the galaxy, think about sending out human colonies. It's natural to think we would explore it just as we do the Earth, it's the only way we know. To send machines instead of humans, especially machines that can replicate, may seem frightening. But - I'd argue, humans colonies are by far the most scary way we could explore the galaxy. It might well be a case of "look out galaxy (and Earth), the monsters are coming" :). 

So what can we do? What is a responsible way to explore our galaxy, with current understanding of science, biology, and society,  and could this explain why our galaxy is not filled right to the brim already with extra terrestrials?

Prolonged spaceflight may give you a nasty case of diarrhea, at least if you are a mouse. Specifically, when mice were subjected to simulated spaceflight conditions, the balance of bacteria and the function of immune cells in the gut changed, leading to increased bowel inflammation.  

What do you say to Pluto’s demotion to “dwarf planet” status?  I did not approve of the demotion, but a few days ago our BBC Sky at Night team did give a reasonable reason why it does require a new category.  With Neptune, one can say “planets end here”, while Pluto is the first of many bodies such as the remarkable Eris that we now know inhabit the Kuiper Belt. 

NASA’s announcement of the discovery of a new extrasolar planet has been met with a lot of excitement.

But the truth is that it is impossible to judge whether it is similar to Earth with the few parameters we have – it might just as well resemble Venus, or something entirely different.

There is so much over enthusiastic hype about this planet today, I thought could do with a bit of more sober reporting of the results, interesting though they are. Much of that speculation derives from just one phrase in the press release I think, where they say:  "Today, and thousands of discoveries later, astronomers are on the cusp of finding something people have dreamed about for thousands of years -- another Earth." The idea of what that means by "another Earth" for astronomers who know the capabilities of Kepler, is rather different from what most of the general public would think of when you say "another Earth".