Sorry for the day's delay on this newsletter, I just returned from the Americal Astronomical Society Meeting in Hawaii. I was supposed to catch the red-eye Wednesday night and get back to work on Thursday. But mechanical difficulties with my airplane kept us on the runway for hours, and they eventually canceled the flight. I got to enjoy a bonus day in Honolulu (mostly sleeping). I'm back now, catching up on everything, and as you can see, it was an avalanche of news. So, enjoy the biggest newsletter I've probably ever done. One of the big topics of conversation at the conference was satellite constellations like Starlink, OneWorld and their impact on astronomy. I heard time and time again from astronomers at how surprised they were by the brightness of the objects in the sky, both in visible light and radio waves. Although they'll get less bright once they reach their final altitudes, they'll still put up about 9x as many bright objects in astronomers' fields of view and for some times of the year, they'll be visible for entire passes. SpaceX has been in consultation with astronomers, and in the most recent launch, they tested out painting one of the satellites with darkening materials to see what kind of an impact that has. We won't know for another few weeks when this newest batch reaches its final altitude.
Starlink is Working to Decrease the Brightness of its Satellites for Astronomers
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Fraser Cain
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Universe Today
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This week's questions show was recorded at the 235th Meeting of the American Astronomical Society in Honolulu, Hawaii. I was lucky enough to have 3,500 astronomers, space scientists and others to talk with. Ethan Siegel from "Starts with a Bang" is back, and this time he's answering your questions about space and astronomy.
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As astronomers look out into space, they're looking back in time. And new images captured by a recent survey have found a galaxy group that was forming when the Universe was only 680 million years old, just 5% of its current age. This discovery is valuable because it reveals a galaxy during the age of reionization, when the first galaxies were blowing away the cosmic fog, allowing light to travel easily through space. Galaxies like this are incredibly useful to astronomers, as they tell us how the biggest structures in the Universe came together, early on in its history.
Galaxy M87 is the home of the famous supermassive black hole captured by the Event Horizon Telescope. This monster black hole creates such a powerful magnetic field in its accretion disk that material is accelerated out of the galaxy at a tremendous velocity - now clocked at 99% the speed of light. This jet stretches about 5,000 light-years into space, and thanks to observations by NASA's Chandra X-ray Observatory, sections have been seen going almost the speed of light.
The Universe isn't just expanding, this expansion is accelerating, thanks to the newly discovered phenomenon of dark energy. The discovery of dark energy was made by measuring the distances to standard candles of brightness - Type 1A supernovae - which should always detonate with the same amount of energy. But a new survey of nearby galaxies showed that the brightness of supernovae might also change depending on the overall age of stars in the galaxy. And when researches accounted for this changing light curve, they found that the need for dark energy goes way. Interesting evidence that there might not be such a thing as dark energy after all.
We're still five years away from the launch of NASA's WFIRST space telescope, which will have the ability to capture the equivalent of 100 Hubble-quality images with each photograph and survey the sky with 1000 times the speed. To help us understand what this observatory will be capable of, and to help astronomers plan their observations, NASA released a simulation that shows what kinds of images we should expect to see from WFIRST. The simulated image shows a region of space in the nearby galaxy M31 containing over 50 million individual stars.
We're all excited for Betelgeuse and other supernova progenitors, but there's another star that should give us a reliable light show: V Sagittae. It's actually two stars, known as a cataclysmic variable, where a white dwarf star is feeding on material from the other main-sequence star. This material is piling up on the surface of the white dwarf, and it should flare up significantly at some point in this century. Over the next few decades, it'll get brighter, eventually appearing as bright as the brightest star in the sky by 2083. Then it'll fade away and go through the process again
NASA's Transiting Exoplanet Survey Satellite has finally found an Earth-sized world orbiting in the habitable zone of its star. Of course, it's not a sunlike star, but a much smaller, dimmer red dwarf star, similar to the discovery of planets around the Trappist-1 system several years ago. The planet is called TOI 700d and it's the fourth most distant planet from the star. Red dwarf stars are known to have killer solar flares, but in 11 months of observations, astronomers didn't see any significant flares from the star, which means it could be much more habitable than other red dwarfs.
China's Chang'e-4 mission is still working away nearly the Moon's south pole, attempting to learn more about the regions on the far side of the Moon. And Chinese researchers released a bunch of data to celebrate an entire year on the Moon. For starters, the Yutu-2 rover has traveled a record-breaking 357 meters on the far side of the Moon, crawling a little more each time the Sun returns for a 2-week lunar day.
Stars are formed within huge clouds of gas and dust, but the actual mechanics of this are still a bit of a mystery since the collapse of a stellar nebula seems to require a kick from a nearby supernova or galactic merger. Researchers have used ESA's Gaia spacecraft to create a huge map of a starforming region that extends about 9000 light-years across and rises and falls about 500 light-years above and below the galactic plane.
Whenever the Milky Way merges with a new galaxy, it unleashes a new wave of star formation. But astronomers were surprised to discover that an upcoming merger with the nearby Large Magellanic Cloud is already starting to trigger star formation in the Milky Way, even though the dwarf galaxy hasn't actually collided with us yet. It appears that a stream of gas emanating from the LMC is much closer to the Milky Way than previously believed, and this is impacting our galaxy, triggering the new star formation.
In addition to the new planet in the habitable zone, TESS also discovered a planet that orbits around two stars, like a real-life Tattoine. The system is called TOI 1338, and it was discovered by NASA intern Wolf Cukier which he was looking at the system which had previously been identified as an eclipsing binary. The planet is 6.9 times bigger than the Earth, making it somewhere in between Neptune and Saturn in size, and it's perfectly lined up with its stars, which means that it sees solar eclipses every 15 days.
Astronomers are locating planets in the habitable zones of their stars, regions where liquid water can form. But it turns out there are better and worse kinds of stars to search for habitable planets as well. And some of the best are known as "K" stars or orange dwarfs. These are a little less massive than the Sun, which means they'll live much longer - as long as 40 billion years since they go through their fuel more efficiently. They're also very stable, without the deadly solar flares that would sterilize planets around red dwarf stars.
Astronomers are still trying to work out the so-called "Crisis in Cosmology", the discrepancy in the expansion rate of the Universe measured at different times in the age of the cosmos. This new technique involves gravitational lensing, using the gravity of a foreground galaxy as a natural lens to observe the light from a more distant object. It provides a completely new number for the expansion rate of the Universe: around 67 km/s/Mpc, which is still different from the accepted 74 km/s/Mpc.
Astronomers have been finding planets in other star systems, and some are very similar to what we've got in the Solar System. But there's a bizarre new class of planets called "super-puff" planets, with the mass of a couple of Earths puffed out to the size of Jupiter. The best example is located in the Kepler 51 system, located 2,615 light-years away in the Cygnus system. It's believed that planets like this will be more common in younger star systems; Kepler 51 is only 600 million years old, compared to the Solar System's 4.6 billion years.
Although it's incredibly hot deep down inside the Earth, it's snowing... iron. Geologists now believe there's a region just within the outer core where tiny particles of iron solidify and fall to form iron snowdrifts as thick as 320 km on top of the outer core. Studying the deep interior of the Earth's core is tough to do, and researchers used seismology to watch how sound waves move through the interior of the Earth. They discovered that the waves move slower than expected when passing through the base of the outer core and faster moving through the inner core. And an iron snow-capped outer core helps explain this discrepancy.
We've talked about Shkadov Thrusters before, building a huge mirror that allows the Sun to push itself around the Milky Way with its light. But another idea, presented by Matt Caplan from Illinois State University suggests you could have an even more powerful way to go about it, using magnetism to harvest hydrogen from the Sun to power a fusion thruster. The idea was animated by the folks at Kurzgesagt to create a really cool video, which you should definitely watch.
We know that Venus had volcanoes in the past, but it doesn't have the same kind of plate tectonics that we have here on Earth. In fact, at some point in the last few hundred million years, the entire surface of Venus seems to have turned itself inside-out. But researchers have found evidence that Venus might have had active volcanoes on its surface as recently as 2.5 million years ago, and there could still be some level of volcanism going on today.
The Moon lacks a magnetosphere today, which means that any humans on the surface of the Moon will have no protection from the harsh radiation from space. But early on in the Moon's history, it might have been a different story. In fact, a new study proposes that the Moon used to have a magnetosphere that was twice as strong as the Earth's, and then it faded away, completely disappearing about a billion years ago. The key to this discovering was finding rocks on the Moon that were older than about a billion years, showing evidence of a lunar magnetosphere locked into their magnetic particles.
This is an absolutely beautiful picture showing the huge clouds of gas and dust at the core of the Milky Way. The image was captured by NASA's airborne SOFIA Telescope, which carries an infrared telescope high above the thickest part of the atmosphere, revealing details which are impossible to get from the ground. One of the mysteries of the core is why fewer massive stars form than expected when there's so much raw material for their formation.
This is the spiral galaxy UGC 2885, as imaged by the Hubble Space Telescope. It looks like a regular spiral galaxy, but it's actually 2.5 times bigger than our own galaxy, with 10 times the number of stars: over a trillion stars. And this is surprising, because a galaxy this big would have gone through many mergers over its billions of years of history. It should look like a mangled elliptical galaxy like M87, but it still has this beautiful, delicate spiral structure.
Astrophotographer Michael Stark (@m_stark2) featured a bunch of deep sky objects that we've never seen on our Instagram channel before, including this object known as the Dolphin Head Nebula, which is caused by a Wolf-Rayet star in the pre-supernova stage.
We have featured thousands of astrophotographers on our Instagram page, which has more than 191,000 followers. Want to do a takeover? Use the hashtag #universetoday and I'll check out your photos.
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