The Sweden Solar System

Earth and Moon

The Last Shuttle, Dan Winters

A vintage NASA-commissioned Rick Guidice painting gives a cutaway view of the inside of a space colony design known as the Stanford torus, a proposed habitat that would house 10,000 to 140,000 permanent residents. The rotating, doughnut-shaped ring could have a diameter of around 2 kilometers, revolving once per minute to give about 1.0g of artificial gravity on the inside of the ring through centripetal force. A massive system of mirrors would provide the sunlight needed for daily activity, agriculture, and so forth. (NASA Ames Research Center)

The last shuttle

Image of Saturn taken by Cassini spacecraft in October 28, 2016.

Credit: NASA / JPL / Cassini

International Space Station flyover

Hey Venus

The leisurely pace of light speed

In a 45-minute video called Riding Light, Alphonse Swinehart animates the journey outward from the Sun to Jupiter from the perspective of a photon of light. The video underscores just how slow light is in comparison to the vast distances it has to cover, even within our own solar system. Light takes 8.5 minutes to travel from the Sun to the Earth, almost 45 minutes to Jupiter, more than 4 years to the nearest star, 100,000 years to the center of our galaxy, 2.5 million years to the nearest large galaxy (Andromeda), and 32 billion years to reach the most remote galaxy ever observed.1 The music is by Steve Reich (Music for 18 Musicians), whose music can also seem sort of endless.

If you’re impatient, you can watch this 3-minute version, sped up by 15 times:

This isn’t strictly true. As I understand it, a photon that just left the Sun will never reach that most remote galaxy.↩

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!