Hubble reveals our young galaxy's riotous behavior, Einstein shows how to play ring around the galaxy and nations join forces to nudge an asteroid off course in our selection of the week's best space-related pictures.
If any Earthlike planets existed 10 billion years ago, every night would have been like an epic rave. At that time, our young galaxy was awash in new star formation, with stellar babies popping up at a rate 30 times higher than they do today. For planets that witnessed this spectacle, the night sky would have been filled with glowing clouds of gas littered with blue-tinged newborn stars, like the scene depicted here in an artist's rendering. Earth, though, would never have witnessed such a riotous sight. An immense galaxy survey conducted with data from the Hubble Space Telescope suggests that our Milky Way galaxy hit its star-forming peak 5 billion years before the sun and its planets were created. But being late to the party may have been good for our solar system—the explosive deaths of older stars seeded the galaxy with plenty of the raw materials needed for rocky planets, and maybe life, to form.
Ice and Fire
Ribbons of brilliant auroras fill the skies over an illuminated igloo at the Churchill Northern Studies Center in Manitoba, Canada. Auroras happen when charged solar particles slam into Earth's magnetic field and get funneled toward the poles. When these particles strike molecules in our atmosphere, they give them a jolt of energy, which gets released as light. Strong solar activity increases the odds of seeing auroral activity, although places within the Arctic Circle are usually best bets. Churchill, for instance, is graced with northern lights almost year-round.
Put a Ring On It
One of the most visually impressive effects described by Einstein's general theory of relativity is the phenomenon called gravitational lensing. According to the famed physicist, gravity can get so strong around very massive objects that it actually warps light. When cosmic objects are lined up just right, the gravity of a hefty body near us can redirect and magnify the light from a more distant galaxy, creating a lens that allows astronomers to see the far-off object in greater detail. In this case, the Atacama Large Millimeter/submillimeter Array (ALMA) observatory in Chile took a look at the known gravitationally lensed galaxy SDP.81. ALMA's view of this so-called Einstein ring offers the most detailed image yet of the glowing gas and dust in a galaxy that is nearly 12 billion light-years away. According to ALMA, the resolution is akin to "seeing the rim of a basketball hoop atop the Eiffel Tower from the observing deck of the Empire State Building"—a distance of about 3,600 miles.
A delicate curtain of sea ice decorates East Antarctica’s Princess Astrid Coast in this image taken by NASA's Terra satellite. The shot was taken on April 5, several weeks after Antarctica had reached its annual sea ice minimum. The ice is now expanding toward its annual maximum, which is predicted to happen in September. Last year Antarctica hit its highest maximum on record, with sea ice around the continent reaching 7.7 million square miles. According to NASA, this is actually on track with climate change models, which predict a short-term increase in sea ice around the southern pole. But things won't look so rosy in the long run, as rising air temperatures near the ocean surface start to overcome the conditions that have been spurring ice formation.
How do you nudge an asteroid off a potentially disastrous path? NASA and ESA think you should throw a dart at it. The two space agencies have started preliminary design work on a mission to the binary asteroid known as Didymos that includes NASA's Double Asteroid Redirection Test, or DART, probe. An ESA spacecraft, called the Asteroid Impact Mission (AIM), is slated to launch in 2020 and reach the asteroid pair in 2022. DART should arrive in the later part of the year, and AIM will collect data as DART deliberately crashes into the smaller of the two space rocks at a speed of about 13,000 miles per hour—envisioned here in an artist's rendering. The collision should help astronomers better understand how asteroids react to being shoved off course, helping them work out best practices for deflecting any actual threat in the future.