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Marcus Tullius Cicero, Aratea (Harley MS 647, ff 2v-17v)

22 constellation figures containing extracts from Hyginus, Astronomica.

England (c. 820-11th century)

This is one of the coolest Illuminated Manuscripts I’ve come across in quite a while. The illustrations of various constellations have integrated the design of each figure into the script, along with various small portraits of famous astronomers. You can view the whole thing here.

A Light in the Dark: Astronomy 101

I’ve written a bunch of posts about awe-inspiring astronomical phenomena, but recently I’ve realised that to some people, it might not mean much. If I—a pretty switched-on person—could have made it through high school without learning the difference between a nebula and a galaxy, then a lot of others might be unsure about the basics too. So, what follows is a quick introduction to the universe and our place within it. 

We’ll start close to home: our planet, Earth, is in a nearly-circular orbit around the Sun. It completes one orbit a year, and every day it revolves once on its axis; we face the Sun during the day, and face the void of the universe at night. So the Earth is orbiting the Sun, and then in turn the Moon orbits the Earth. It takes 28 days to complete an orbit, and its phases depend on where its position relative to the Sun.  

The Sun sits in the centre of the solar system. The four closest planets, from inwards out, are Mercury, Venus, Earth, and Mars, but they’re still millions of kilometres from the Sun, with millions of kilometres between each planet too. These are called the terrestrial planets because they’re rocky in composition. Past Mars is the asteroid belt, where a smaller, rocky bodies zoom around the Sun in their own orbits. Beyond this are the Jovian planets, or the gas giants: Jupiter, Saturn, Uranus and Neptune. Jupiter is the largest, with massive storms and wind currents raging in its thick, deep atmosphere; Saturn and Uranus boast rings made up of ice and dust; and Neptune is one of the coldest places in the solar system. 

Beyond these planets are a few dwarf planets, including Pluto, and then the Kuiper belt, which contains thousands of icy objects and short-period comets. Finally, the last stop in the solar system is a huge halo extending right around the edge. Called the Oort cloud, it’s home to long period that take thousands of years to orbit the Sun. 

Our Sun is a star, a vast sphere of hydrogen so hot and pressurised that at its core, nuclear fusion takes place. Hydrogen atoms are fused into a helium atoms, and in the process release energy—the energy we could not live without. 

Our Sun is part of a bigger collection of stars called a galaxy, bound together by the force of gravity. When I say “collection”, I don’t just mean ten or fifty—most galaxies are home to billions of stars of different sizes and ages; some only have a few thousand but others have trillions. Our own galaxy, the Milky Way, contains around 100 billion stars. We live in a spiral galaxy, located on one it its outer arms, but galaxies come in different shapes—not just spiral but also barred, elliptical, and many others. 

In the spaces between stars, galaxies also contain clouds of gas and dust called nebulae. Under the influence of gravity, this gas and dust can clump together until there’s enough material to collapse into a hot, pressurised ball—and when nuclear fusion ignites, a star is born. 

There are over 100 billion galaxies in the observable universe, organised into groups or clusters. We’re part of the imaginatively named Local Group. These clusters are then organised into superclusters, and then on the biggest scales in the universe, these superclusters are organised into filaments and sheets. Between these filaments are voids of such enormous immensities that it’s hard to imagine. 

Along with dark matter and dark energy, planets, stars, nebulae, and galaxies make up the Universe—everything that exists. The Universe is approximately 13.8 billion years old and is rapidly expanding. The ultimate fate of the Universe is unknown, but we still have plenty of time to explore astronomy’s endless mysteries.

The Butterfly Nebula from Hubble  : The bright clusters and nebulae of planet Earths night sky are often named for flowers or insects. Though its wingspan covers over 3 light-years, NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the dying central star of this particular planetary nebula has become exceptionally hot, shining brightly in ultraviolet light but hidden from direct view by a dense torus of dust. This sharp close-up of the dying stars nebula was recorded in 2009 by the Hubble Space Telescopes Wide Field Camera 3, and is presented here in reprocessed colors. Cutting across a bright cavity of ionized gas, the dust torus surrounding the central star is near the center of this view, almost edge-on to the line-of-sight. Molecular hydrogen has been detected in the hot stars dusty cosmic shroud. NGC 6302 lies about 4,000 light-years away in the arachnologically correct constellation of the Scorpion . via NASA

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Liftoff! US, Russia Launch Historic One-Year Space Mission

An American astronaut and Russian cosmonaut launched into space Friday to attempt something their two countries have never done together before: a one-year mission on the International Space Station that could help one day send humans to Mars.

The epic one-year space mission launched NASA’s Scott Kelly and cosmonaut Mikhail Kornienko into orbit aboard a Russian Soyuz space capsule at 3:42 p.m. EDT (1942 GMT) today (March 27) from the Baikonur Cosmodrome in Kazakhstan, where it was early Saturday morning local time. Also flying on the Soyuz is cosmonaut Gennady Padalka, a crewmember who will live and work aboard the orbiting outpost for about six months, the usual length of time people spend on the station.

“A year in space starts now,” NASA spokesperson Dan Huot said at launch. You can check out a video of the history-making launch as well. [The One-Year Space Mission: Full Coverage]

Continue Reading.

Type la supernovae

A new study analyzes several sites where dead stars once exploded. The explosions, called Type Ia supernovae, occurred within galaxies, six of which are shown in these images from the Sloan Digital Sky Survey.

Type Ia supernovae, which occur when burnt-out stars called white dwarfs detonate, have been used for years to help measure the distances to galaxies and the acceleration of our universe. But the tools aren’t perfect, so researchers are analyzing the sites of the explosions to learn more about them and improve cosmic measuring tools.

Using data from NASA’s Galaxy Evolution Explorer, or GALEX, astronomers were able to show that a fraction of the Type Ia explosion sites they looked at are associated with hot young stars. This means that those areas are young in general, and that the explosions happened when relatively young white dwarf stars exploded.

Photo credit: SDSS