Space

You've probably seen movies of orbital space habs spinning for artificial gravity. But did you know, that nobody has ever tested this to see how it works out in practise? We know that weightlessnes is bad for health, especially long term, with many potentially serious medical issues. But do we need full g, or Mars g, or lunar g to stay healthy? Nobody knows. Can we cope with a spinning hab a few meters across or do we need to think about a huge hab or tether system a couple of hundred meters across or larger? Again nobody knows. 

Stars like Sol are relatively easy to understand, because they are numerous, and live for billions of years, but high mass stars are rare and live for only a few million years. As a result, understanding their early evolution has been a challenge.  

Simple models suggested that when high mass stars become hot enough to ionize the gas around them, heating it to thousands of degrees, the gas will quickly expand. But decades ago, astronomers found that regions of ionized gas around young high mass stars remain small (under a third of a light-year) for ten times longer than they should if they were to expand as predicted. 

In 2005,the Japanese spacecraft Hayabusa  revealed that the near-Earth asteroid (25143) Itokawa  has a strange peanut shape, leading to questions about why. Now, using ground-based observations, a group has measured the speed at which Itokawa spins and how that spin rate is changing over time and combined these observations with theoretical work on how asteroids radiate heat.


Kepler-413b is located 2,300 light-years (about 700 parsecs) away in the constellation Cygnus. It circles a close pair of orange and red dwarf stars every 66 days but what really makes Kepler-413b unusual is that it precesses wildly on its spin axis - The tilt of the spin axis of the planet can vary by as much as 30 degrees over 11 years with respect to the plane of the binary star's orbit.

Compare that to the Earth's rotational precession, which is a far more modest 23.5 degrees over 26,000 years. This far-off planet is far-out and all of this complex movement leads to rapid and erratic changes in seasons.  That it is precessing on a human timescale is simply amazing. 

The linchpin location of the "Star Wars" franchise was the planet Tatooine, home to both Luke Skywalker and Obi-Wan Kenobi. It, along with its twin suns, appeared in every movie of the franchise except "The Empire Strikes Back".

How would such a planet, orbiting two stars, form? There are few environments more extreme than a binary star system, if you are forming a planet. 

Kepler-34(AB)b has some answers, according to a new study. Like Tatooine, Kepler-34(AB)b is a circumbinary planet, its orbit encompasses two stars. Since powerful gravitational perturbations from two stars lead to destructive collisions that grind down planetary material, the existence of such planets can be difficult to explain.


The search for extraterrestrial life goes on, sort of. We do it, as half-heartedly as we do anything in space, because we're more afraid of being alone than finding another civilization. Or vice versa.

But we may not be looking in the best spots, even if we are looking in the Habitable Zones. Looking for planets or moons outside the "stellar habitable zone" might lead to environments that are even more favorable to supporting life than here on Earth, according to a crazy/insightful article in Astrobiology. These superhabitable worlds might have unique characteristics and be ideal targets for extrasolar exploration, the authors speculate, though that won't mobilize a lot of policymakers. 


We know now that asteroids are relics that can tell us what the planets in our solar system may have been like before they formed cores and mantles and crusts. But that wasn't always the case. Until the past few decades asteroids were viewed in a more static way. Those that formed near the sun remained near the sun, those that formed farther out stayed on the outskirts.

Then it was discovered that some asteroids have compositions that don't match their locations in space. Those that looked like they formed in warmer environments were found further out in the solar system, and vice versa. Anomalous "rogue" asteroids.


Why were there old, enormously massive galaxies no longer forming new stars in the very early universe?

The first stars already emerged in the very early universe about 200 million years after the Big Bang. Gas is the raw material used to form stars and giant clouds of hydrogen and helium and dust (and whatever "dark matter" will eventually be) contracted and eventually the gas became so compact that the pressure heated the matter so that glowing gas balls were formed and new stars were born. 


We have learnt so much about the geology of other planets. Our spacecraft have discovered ancient oceans and rivers on Mars, and have found possible habitats for life. But we haven't discovered this life itself, and we know nothing at all about extraterrestrial biology. Why is life so hard to spot? Is it there at all, and if so, why is it hidden from view, and how can we find it?

One of the best places to look for this life might be here:

NGC 5194, also known as M51, the Whirlpool Galaxy, is one of the most spectacular examples of a spiral galaxy, with two spiral arms curling into one another in a billowing swirl, this galaxy hosts over a hundred billion stars and is currently merging with its companion, the smaller galaxy NGC 5195.

Around 30 million light-years away, the Whirlpool Galaxy is close enough to be easily spotted even with binoculars. Using the best telescopes available both on the ground and in space, astronomers can scrutinize its population of stars in extraordinary detail.