Astronomy – Little Bits of Science

The Wow! Signal

Proving that there is still much about the universe we don’t know, the Wow! signal from 1977 confounds to this day. So what is the Wow! signal, and why is it still of interest roughly 40 years later?

Should another civilization somewhere in the universe want to communicate with us and announced their presence, it is theorized that these alien beings will most likely broadcast at 1420 megahertz (MHz), a natural emission frequency of hydrogen. The thinking is that given hydrogen’s natural abundance in the universe, all intelligent creatures will be aware of it and therefore attempt to communicate at this natural emission line. So back in the 1970s, when Ohio State University was re-purposing the Big Ear telescope in Delaware, Ohio to help with SETI, the telescope was tuned to watch the 1420 MHz frequency.

Big Ear was set to scan the sky in 72 second intervals, changing locations scanned after that time due to the earth’s rotation. The signal was only heard on a single frequency with no accompanying static on surrounding frequencies. A signal created from something in nature would normally be expected to have static along with the signal.

The signal also “rose and fell” during the 72 seconds, as would be expected from something originating in space. When the radio telescope is pointed at the sky, any such signal will appear to increase in intensity as it first moves across the observational beam of the telescope, then peak when the telescope is pointed straight at it and then decrease as it moves away from the telescope. This also makes a mere computer glitch a less likely explanation, although not impossible.

Subsequent checks in the same approximate area for additional signals have turned up nothing. So we haven’t seen anything that helps us determine for certain if this is a natural “noise” from elsewhere in the universe or if it was created by another intelligent species.

However, recently Professor Antonio Paris of St. Petersberg College in Florida has put forward a hypothesis as to what the Wow! signal really is. He believes it could have been reflections from one of two comets believed to be in the area of the Big Ear’s orientation back in 1977. And he’s crowdfunding the money needed to test his hypothesis.

Comet 266P/Christensen will pass the Chi Sagittarii star group again on 25 January 2017, while 335P/Gibbs will make its passage on 7 January 2018. Paris plans to observe these events to look for a recurrence of the mystery signal. But time is not on his side for using an existing radio telescope – they are all booked out.

So by this time next year we should be able to tell if Professor Paris is right or not. Look for a follow-up then. In the meantime, if you’d like to hear more about the Wow! signal, I recommend a read or listen to the Skeptoid Wow! episode which better covers much of what we know or think we know about the signal.

No, we haven’t found an alien mega-structure yet

Over a year ago, scientists announced that they were baffled by the apparent dimming of star KIC8462852, also known as Tabby’s star. Now this is not a newly discovered star, but rather one that has been known for well over a hundred years. And that age of the star is part of what contributes to the mystery around it. See, when the star was first discovered, it was brighter than it is now. And while that isn’t unusual for a young star, KIC8462852 is understood to be a mature star – a definition that varies according to how massive the star is, but is generally millions or even billions of years.

Of course, the intarwebz came to the rescue of these poor researchers, putting forward the inescapable conclusion that what we were seeing was evidence of an alien mega-structure, most likely a Dyson Sphere. That is to say, the popular opinion online has been that the light from the star is blocked periodically by a partially built structure which surrounds star KIC8462852 and harnesses much/most of the energy output of the star, converting it to some other energy form for the advanced technology built by the aliens living near the star. Naturally, there is no other possible explanation, and clearly we’ve finally found evidence of other life in the universe.

The so-called alien megastructure hypothesis persisted longer than most extra-terrestrial-based theories, simply because scientists had few alternative ideas to explain the star’s peculiar blinking – until now. And the latest theory is almost as intriguing as the alien hypothesis.

Except, of course, that’s likely not what we’re seeing. The prevailing opinion now among experts is that we were witnessing the tail end of KIC8462852 consuming one of its own planets, brightening as a result of the added fuel, and slowly dimming back to its natural magnitude over the past hundreds or maybe thousands of years.

If KIC 8462852 did eat a planet – which is extremely rare in the space world, unless a collision pushed the planet out of its orbit – the star’s brightness would increase for a short period of 200 to 10,000 years as it burned up the planet (short in star time, that is). But once the burning was complete, the star would go back to around its original level of brightness.

So while the Dyson Sphere hypothesis is more fun, the more likely explanation is still fascinating, and gives us more information towards building a better understanding of our universe.

Hearing from Hitomi Again!

So earlier in the life of Little Bits of Science, I wrote about the Hitomi satellite, at the time apparently lost in space. It turns out that the day after I wrote about it, Hitomi was heard from again!

Junked? Maybe not. Hitomi, a Japanese astronomy satellite, was thought to be lost after it failed to come online. Now the Japanese Aerospace Exploration Agency says the satellite has phoned home – but a full recovery will take months.

What does this mean, exactly? Well, it’s too early to say, even now a month since we’ve heard from the satellite. According to communication that scientists have since gathered from Hitomi – infrequent beacon signals which have been picked up – it appears the satellite is still there, just spinning out of control. And apparently, this is a recoverable situation. The Japanese space agency responsible for the satellite is working on restoring communication and stabilizing it so Hitomi can return to its mission of X-Ray observation of the universe.

What Happened to the Hitomi Telescope?

Launched on February 17th, the Hitomi telescope is an X-Ray telescope commissioned by the Japanese Aerospace Exploration Agency (JAXA). While everything looked fine for the telescope during testing done since launch, when it was time to power up for real work this past Sunday, the satellite was strangely quiet.

Engineers have been unable to determine the health of the satellite since the sudden disruption in communications, JAXA said, although ground controllers received a brief signal from Hitomi.

Shortly after the go-live time, the US Joint Space Operations Center, which tracks space debris, picked up 5 objects orbiting near where the satellite was or was supposed to be. Work is now underway to determine what happened to the Hitomi, as well as to see if the 3-year mission can be salvaged or not.

Whatever the cause of the problem, don’t count Hitomi out yet. “The interesting thing about the Japanese is they tend to be very good at resurrecting things that would otherwise be dead,” says Jah. For instance, JAXA recently maneuvered the Akatsuki satellite into orbit around Venus, after the probe had been adrift in space for five years.

NASA Sees Monster Stars

Thanks to another amazing photo by the Hubble telescope, scientists have discovered the largest stars we have ever seen.

The image shows the central region of the Tarantula Nebula in the Large Magellanic Cloud. The young and dense star cluster R136 can be seen at the lower right of the image. This cluster contains hundreds of young blue stars, among them the most massive star detected in the Universe so far. Using the NASA/ESA Hubble Space Telescope astronomers were able to study the central and most dense region of this cluster in detail. Here they found nine stars with more than 100 solar masses.

An international team of scientists using the NASA/ESA Hubble Space Telescope has combined images taken with the Wide Field Camera 3 (WFC3) with the unprecedented ultraviolet spatial resolution of the Space Telescope Imaging Spectrograph (STIS) to successfully dissect the young star cluster R136 in ultraviolet light for the first time.

ScienceCast: Amazing Moons

NASA presents a video about the moons in our galaxy:

On Gravitational Waves

I’ve been reading a bit today about this recent discovery of gravitational waves from LIGO. My hope was to get enough of an understanding of what gravitational waves are to explain them to readers here. Turns out, I can’t do a better job of explaining them nor covering the discovery than what this Science News video does, so I’ll just share it rather than try to do better:

I can tell you that gravitational waves are effectively ripples in the fabric of spacetime, spreading much like ripples on the surface of a pond do when a rock is tossed into the pond. They were predicted about a century ago by Einstein as part of his Theory of Relativity, although apparently he didn’t think we’d ever have the technology to detect them. For measurable gravitational waves to even make it to earth, a massive ripple has to be started by an enormous release of energy, such as what happens during the collision of two black holes.

To find out more, read the links offered up above. And if you are interested in helping find more gravitational waves, download and install the Einstein@Home screensaver and make your own contribution to science!

The James Webb Space Telescope

This is a massive scientific undertaking. Here’s hoping the lessons learned from the Hubble launch aren’t repeated for this telescope. The telescope will travel a million miles after launch, making repairs significantly more difficult (née impossible). james webb photo Even after it arrives at its destination, the telescope will have to unfold and cool over another month before it is operational and we will know that it will work as expected.

If you want to keep an eye on the Webb, check out NASA’s live camera view of work as it proceeds on the telescope.

Photo by NASA Goddard Photo and Video

Volcanic Explosion Tilted Mars

Billions of years ago, a volcanic explosion occurred on Mars which was so massive it actually tilted the planet:

That volcano—the Tharsis volcanic dome—is 96.3 miles by 77.7 miles. When it exploded all those years ago, it disrupted the mantle and crust of the planet (though not the rest of the interior), shifting the whole outside crust up 25 degrees. When the volcano exploded, it did so with a mass of a “billion billion” metric tons of matter, or 1,000,000,000,000,000,000 metric tons.

This explosion may have also lead ultimately to the liquid water which is now evidenced on the planet’s surface.

Mysterious Fast Radio Bursts

Arecibo photo Recently, scientists have seen fast radio bursts coming from the same direction as one spotted in 2012. Initially announced in 2007, fast radio bursts are “millisecond chirps of radio waves pinging through the heavens” which were never seen in the same place before.

While some published research says we’ve solved the mystery of these fast radio bursts, others are not so sure:

Ultimately, astronomers need to make more measurements of these fleeting signals to figure out the puzzle. Arecibo is the most sensitive radio telescope in the world, which could be why it is the only one to have picked up repeated FRBs.

Whatever these mysterious bursts are, we have at least identified a patch of sky where they have repeated a fair number of times, and this tells us that the cause of the bursts isn’t destroyed in the process of making them.

“The fact it repeats rules out—for this object anyway—any of the models that are just one-offs, whether they involve mergers or evaporating black holes or something else,” says study co-author James Cordes, an astronomer at Cornell University. Instead, Cordes says, the more probable culprit is some sort of powerful outburst from a rotating neutron star.

The trouble is, no neutron stars have ever been seen behaving quite as strangely as the one Cordes guesses might be behind these FRBs

Photo by matt.terich