2,000 Light Years From Hone, Ceres

The Sun rises over Earth in a postcard illustrated by Soviet cosmonaut Alexei Leonov, recalling the 1965 mission when he became the first human to walk in space.

latest Pluto images released Sept 10, 2015 by NASA. Second to last is Pluto’s moon Charon. Last is the original “up close” image of Pluto. Images taken by NASA’s New Horizons Spacecraft.

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Neutron Stars and Nuclear Pasta. Yummy!

The latest video from Kurzgesagt is a short primer on neutron stars, the densest large objects in the universe.

The mind-boggling density of neutron stars is their most well-known attribute: the mass of all living humans would fit into a volume the size of a sugar cube at the same density. But I learned about a couple of new things that I’d like to highlight. The first is nuclear pasta, which might be the strongest material in the universe.

Astrophysicists have theorized that as a neutron star settles into its new configuration, densely packed neutrons are pushed and pulled in different ways, resulting in formation of various shapes below the surface. Many of the theorized shapes take on the names of pasta, because of the similarities. Some have been named gnocchi, for example, others spaghetti or lasagna.

Simulations have demonstrated that nuclear pasta might be some 10 billion times stronger than steel.

The second thing deals with neutron star mergers. When two neutron stars merge, they explode in a shower of matter that’s flung across space. Recent research suggests that many of the heavy elements present in the universe could be formed in these mergers.

But how elements heavier than iron, such as gold and uranium, were created has long been uncertain. Previous research suggested a key clue: For atoms to grow to massive sizes, they needed to quickly absorb neutrons. Such rapid neutron capture, known as the “r-process” for short, only happens in nature in extreme environments where atoms are bombarded by large numbers of neutrons.

If this pans out, it means that the Earth’s platinum, uranium, lead, and tin may have originated in exploding neutron stars. Neat!

There Are Way More Rogue Planets Than We Thought

The galaxy is wild. Our solar system, with its surprising abundance of living creatures and nonstop radiation and asteroid showers, is a placid, private garden compared to the rest of it.

In particular, there are perhaps trillions of rogue planets (planetary bodies ranging from little rocky Earth-sized guys to super-Jupiter gas giants) in the Milky Way, including a surprisingly large fleet of the things right near the galactic core.

This is unusual, since the typical way we detect exoplanets is by marking their repeated procession across a star. But rogue planets, by definition, don’t orbit stars. So the way astronomers find them is a little different, requiring use of gravitational microlensing.

Gizmodo breaks it down:

Data gathered by NASA’s now-retired Kepler Space Telescope has revealed a small population of free-floating planets near the Galactic Bulge. The new finding raises hope that a pair of upcoming missions will result in further detections of unbound planets, which drift through space separated from their home stars….

It’s impossible to know what the conditions are like on these presumed rogue exoplanets, but [astronomer Iain] McDonald said they could be “cold, icy wastelands,” and, if similar in size to Earth, their surfaces would “closely resemble bodies in the outer Solar System, like Pluto.”

The new paper suggests the presence of a large population of Earth-sized rogue planets in the Milky Way. It’s becoming clear that free-floating planets are common. McDonald said his team is currently working to come up with a more precise estimate for how many of them might exist.

Did you catch that part about how McDonald’s team made this discovery using a now-retired telescope? Yeah. Apparently the new telescope projects coming online are both more powerful and (in particular) better equipped to detect gravitational lensing effects, and therefore more likely to detect rogue planets in the future.

One way the universe might end

My favorite astrophysicist Katie Mack recently reposted a Cosmos article she wrote about a relatively obscure model for the total annihilation of the universe, called “vacuum decay.”

Essentially, what vacuum decay relies on is the fact that we don’t know for sure whether space is in the lowest energy, most stable possible state (a true vacuum) or at an adjacent, slightly higher energy level (a false vacuum). Space could be only metastable, and a random quantum fluctuation or sufficiently high level energy event could push part of the universe from the false vacuum to the true one. This could cause “a bubble of true vacuum that will then expand in all directions at the speed of light. Such a bubble would be lethal.”

It’s compellingly badass, and as Mack notes, frightfully efficient. First, it’s not the slow petering out that is heat death. Also, it wouldn’t just eliminate our current universe, but all possibility of a universe anything like ours. Vacuum decay destroys space like Roman generals salting the earth at Carthage.

The walls of the true vacuum bubble would expand in all directions at the speed of light. You wouldn’t see it coming. The walls can contain a huge amount of energy, so you might be incinerated as the bubble wall ploughed through you. Different vacuum states have different constants of nature, so the basic structure of matter might also be disastrously altered. But it could be even worse: in 1980, theoretical physicists Sidney Coleman and Frank De Luccia calculated for the first time that any bubble of true vacuum would immediately suffer total gravitational collapse.

They say: “This is disheartening. The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in a new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it.

"However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some creatures capable of knowing joy. This possibility has now been eliminated.”

Exercising in space – Quick video about my favorite fitness machine

#Fitness is critical in space! Watch this #SpeedyTime video as I transform the multi-modal ARED machine during my workout. The Advanced Resistive Exercise Device (ARED), simulates free-weight exercises in normal gravity. In space we exercise 2 hours every day in order to maintain our muscle and bone mass. Our favorite part about exercising in space is of course, the view!

To learn more about the ARED, please visit https://www.nasa.gov/mission_pages/station/research/experiments/1001.html

Milky Way Over Mt. Bachelor - Mitch Darby

Where did the Moon come from?

The Moon is about 40 to 140 million years younger than the Earth and its geology offers broad hints that it was formed in an impact. This is called the giant impact hypothesis.

Nobody can be sure what actually happened, but computer simulations provide some clues. In one simulation, the newly-formed Earth suffers an impact with another planet (called Theia, a little larger than Mars). Theia is torn apart, its core dragged down through Earth’s interior to merge with the Earth’s core. Much of Theia’s mantle is absorbed into Earth’s mantle, and the side of Theia furthest away from the impact is hurled into space. About half the material ejected by the collision is lost and the rest accretes to form the Moon.

The Earth’s axis is tilted, and it is left spinning faster than it does today. A day lasts about ten hours. Months are much shorter too, as the new Moon orbits the Earth much faster. It is also much closer. Had there been anyone on Earth to observe it, they would have glimpsed a Moon twice the present size in the Earth’s primitive sky.

The Moon has since slowed the Earth’s spin, and it is moving away from us at a rate of almost 4 centimetres a year.

You can learn more about the birth of our Moon via Origins: The Scientific Story of Creation by Jim Baggott, or by following #BaggottOrigins across social media.

Image: Moon, by Yutaka Tsutano. CC-BY-2.0 via Flickr.