A Sliver of Golden Light

Oftentimes astronomy can seem like a distant field. We do not study specimen in petri dishes or mix chemicals in a lab. Instead we turn our telescopes to the remote heavens and rely primarily on the light we receive from the universe. Yet sometimes the distant has a profound local impact. This is distinctly seen during a solar eclipse. As one of my friends remarked, it is only at times like this that you really think about how fast the Earth rotates.

On August 21st, 2017, the shadow of the moon swept across the continental United States and inspired millions of people to look up and contemplate the motions of celestial bodies. Here in Bloomington, Indiana, a CelestFest was held on campus. Despite the pesky clouds, questionable music, and shortage of solar glasses, the sight was still impressive.

The shadow of the International Space Station passing across the sun while partially eclipsed by the moon.
Image credit: NASA/Joel Kowsky

It was a hot day, in the low 30s Celsius, with a steady breeze that didn’t really cool us off. Even when the clouds rolled in, we were sweating; only when the moon was covering most of the sun were we not melting. Although we did not experience totality, the temperature drop was noticeable.

In addition to the temperature, the sky darkened around us. The saturation of the world decreased and the contrast slider similarly modified on a cosmic photoshop. The color shift was subtle; I would not have noticed if I did not know to look for it, but the differential was enough to cause the automatic street lamps around campus to turn on.

The sun partially eclipsed by the moon, but also obscured 

partly by clouds. Image credit: Jennifer Sieben

Looking through the solar glasses, it was possible to see a thin sliver of golden light unobscured by the passage of the moon. The crescent slowly shifted from the left side, up around the top and then to the right. I did not have great luck recording with my video camera, a combination of poor focus and a haphazard filter left an oversaturated image that only had a well defined crescent when dimmed by passing clouds.

However, we were able to make different pinhole cameras, even using just our hands to produce a crescent of light on the table. My favourite was seeing the many crescents from my sunhat dotted across my leg. This worked the same as a pinhole camera, showing a small version of what light is passing through the tiny hole. Since the sun is the dominant light source, that is what we see through the hole.

Through the holes in my sunhat 

I was able to see thin crescents of light from the partially 

eclipsed sun against my leg. Image credit: Jennifer Sieben

For added science, our table set up a solar panel to track the energy output of the sun. A large arrow rotated to show the decrease in energy. As of this writing I have not seen the data yet, but it dropped by at least 50%. Cloud cover dropping it to zero made it hard to judge by eye.

Unfortunately since I could not see totality, I was not able to see the corona. The corona is analogous to the outer atmosphere of earth–a gaseous envelope of highly charged particles. Telescopes such as SOHO regularly study the corona and look for coronal mass ejections such as those seen in the image below. Not every ejection is on this scale.

Masking the majority of the sun allows instruments such as the Solar and Heliospheric Observatory (SOHO) to study the corona of the sun. This image shows a large coronal mass ejection (CME) from 6 November 1997. Image credit: SOHO (ESA & NASA)

During the eclipse, the one opportunity for humble earthlings to see the corona for themselves, there was a modest sized prominence at about two o’ clock. Prominences are caused by disturbances in the magnetic field deeper down in the star. This stirs up material and sometimes it escapes from the surface of the sun to arc into space.

At nearly complete totality only a sliver of light is still seen of the photosphere on the right edge of the sun. Solar prominences are seen bursting forth from the surface of the sun as a result of turbulent magnetic fields. Image credit: Robert Stephens

Despite not seeing totality, I was nonetheless thankful that the clouds parted to allow for a view of the distant incandescent crescent. I do plan to chase down totality in seven years, but I will still have good memories of my first solar eclipse.

Seven Dwarfs, err, Planets

Summary: In a brand new press release from NASA, the agency has announced a discovery of seven Earth-sized planets, in the habitable-zone, around a single star. This is the largest star system with such properties and I am excited. The discovery was made by the Spitzer Space Telescope and follow up with ground based observatories.

To be fair, only three of these planets are definitely in the habitable zone, but with the right atmospheric conditions, all seven are likely to have liquid water. This exoplanet system has been called TRAPPIST-1 and the densities show that all planets are likely to be rocky planets like the inner planets of our own solar system. Unlike our sun, this star is an ultra-cool dwarf star that allows all of these planets to be closer to their star than Mercury is to our star. With all of these planets being so close, it is possible that an individual standing on the surface of one planet may be able to look up at the sky and see geological features on the neighboring planet without the aid of binoculars. We can barely do this with our own moon despite how close it is.

If you wanted to visit this system, it is relatively close to us, at only 40 light-years away in the constellation of Aquarius. But until we invent better spacecraft we can only take advantage of the nearness by turning more telescopes to the system. Hubble and Kepler are doing follow-up observations and, when it launches, the James Webb Space Telescope will collect further data.

NASA press release
360 VR of exoplanet surface
Nature

Artist's conception of the system based on known diameters, masses, and orbital distances, NASA JPL, Caltech

One More Shot

Summary: The Cassini spacecraft is on the last phase of its mission. It has begun a series of extremely elliptical orbits around Saturn before it will ultimately plunge into the planet and self-destruct. But while it is still working, there is data to collect. Already we have seen new images of the hexagonal clouds at the North pole of the planet and we are getting new images of the rings. But there is one object in particular that some astronomers have their sights set on.

First noticed in 2013 as a long, bright smudge along Saturn's A-ring, the mysterious object, known as Peggy, is one of the new image goals of the mission. There is no clear image of this smudge yet, and it would be a long time before another mission had a chance to photograph this mystery. The team only has until September to get the image, but thankfully Cassini will be flying close to this A-ring and the mysterious object has now been made into one of the last objectives for the mission.

Saturn can sometimes be used as a model for exoplanet formation in other star systems. The rings act similarly to how we believe dust gathers around a star until planets are formed. It is hoped that by studying Peggy more closely, we will gain more insight into the earliest stages of planet formation. Specifically it is hoped to be a model for how planets migrate. In the few years since Professor Carl Murray discovered this object, astronomers have been able to track it's motion and observe as it has drifted closer and further away from Saturn by a few kilometers.

Even more interesting, as scientists looked back through archival data with recent data from Cassini, they discovered that Peggy might have recently broken into two objects. Recent data shows another, smaller object following directly behind Peggy and orbital dynamics seem to indicate that they would have met in early 2015. Now there is the possibility that a collision of some sort caused both the fracturing of Peggy and also the new orbital radius.

Along with hoping to take better resolved images of Peggy, Cassini scientists also hope to determine the mass of Saturn's rings. Dr. Linda Spiker, the project scientist, points out that the mass can provide key clues about the age of the rings. This in turn would help with models of how the moons were formed. With lots of exciting science coming from the ringed planet this year, this is shaping up to be a great year for astronomy.

BBC News

New Images from esa Mars mission

Summary: Although the Schiaparelli lander was not as successful as hoped and plummeted into the surface of Mars rather than gently landing, the satellite it was released from is still working and returning new images of the surface of the planet. This Trace Gas Orbiter (TGO) is orbiting the planet and using it's impressive cameras to send us back images with a resolution of 2.8 metres per pixel. The camera's principal investigator, Nicolas Thomas, compared it to "flying over Bern at 15,000km/h and simultaneously getting sharp pictures of cars in Zurich."

Other sensors on board will also be investigating the atmospheric gases and looking for water vapor, nitrogen dioxide, and sulphur dioxide among other chemical species. The goal is to detect possible signs of microbial life on the surface and detect the presence of hydrated minerals.

Source and images

Gaia and a new Age of Universe

Summary: The study of astronomy is an old one, but as headlines show, it is a constantly changing field. As our instruments change, we discover that the numbers we thought we knew need some readjustment. In this case, the Gaia space craft from the esa is forcing astronomers to look about the expansion rate of the universe. Again.

This is not the first time there have been some discrepancies in the estimate for the age of the universe. But Gaia is one of the most precise telescopes we have at the moment. Just recently it published precise coordinated for one billion stars. This is leaps ahead of the last survey of this type.

Gaia's estimate of the age of the universe is based upon Cepheid variable stars. These stars pulse with a very specific brightness and rate of pulsation. This makes it easier to tell how far away they are from us and to determine the age of the stars nearby. Gaia has precisely found 212 of these Cepheid stars and with these data, Professor Reiss's team calculates a Hubble constant of 73km/Mpc. This is about the same as they calculated with Hubble data. But it is not the same number found in most textbooks as the accepted value. And it is not due to outdated textbooks. It is because of the methods used to solve for the Hubble constant. The Planck mission gives a much lower value of 66.9km/Mpc.

Why is there such a discrepancy? We aren't entirely sure, but we can probably place a lot of the blame on dark matter. Hopefully as Gaia continues forward on it's mission, we will be able to narrow down the range of possible Hubble constants, and thus the age of the universe and no longer have a few hundred million year gap. Maybe we will even be able to place stricter bounds on what dark matter actually is and what effect it has on our universe.

Source

Also, the Ig Nobel prizes were awarded this week and they are, as always, amazing.

Juno update

Summary: After 5 years and 1.8 billion miles, the Juno spacecraft has made its first flyby of Jupiter. At only 2,500 miles above the cloud tops, this is the closest any spacecraft has come to the gas giant of our solar system.

One of the things that makes Juno exciting is the panoramic colour camera which allows for stunning images to be sent back in addition to data from its other instruments. 

Juno will make 35 further flybys in order to measure Jupiter's water content, magnetic fields, and to look for the possibility of a solid core. Will all of this new data, it is hoped that scientists will have a better idea of how the planets formed in the early solar system.

BBC News

Gravitational Wave Astronomy is here!

Summary: For those of you not glued to your computer for the past couple hours, you may have missed the new announcement from the LIGO experiment. They have officially announced the discovery of a second gravitational wave detection. That's right, it is no longer a single event in the dark. We have two confirmed black hole mergers that created gravitational waves and another "trigger" event that may prove to be an additional gravitational wave source after a few more tests are performed. There's only an 85% chance of the signal being astrophysically significant right now and that is not good enough for the team at LIGO.

I for one am ecstatic about this announcement. Not only does it herald in a new field of astronomy, but the presentation of data so far has been very easy to understand. Great graphics and explanations.

To give a brief outline of how they conduct their science, it starts with an interferometer. Light travels down two paths of equal length before recombining at a photodetector that measures how much light is hitting the sensor. If the paths are truly equal in length, the light from the different paths will cancel each other out and it will be dark. Any little alteration in the length will cause light to be detected. The gravitational waves actually move space itself like a ripple in a still pond so as the wave flies through Earth, the different paths the light travels at will briefly be different.

The first signal in September was unexpectedly loud so it was able to be seen with human eyes, but this new one from December (Christmas in the US!) was harder to spot. They needed the computer to match the signal to a template in order to see it. It works like a child taking a circular puzzle piece and trying all of the different shaped slots until they finally are able to fit it into the corresponding circular depression on the board.

We can only imagine how much great work will still be coming out of this observatory in the future. This is not yet running at full potential and when the second run starts this autumn it will be more sensitive still. I'll be sure to keep you updated.

LIGO
Video of event

Also, if you are interested in helping LIGO look for more gravitational waves, check out GravitySpy.org

Expanding Expansion

Summary: Based on new data from the Hubble Space Telescope, the universe might actually be expanding faster than previously thought. This new data comes from an updated study of the velocities of Cepheid Variable Stars and Type Ia Supernovae to determine a value for the Hubble constant. The new data points to a slightly higher value of 73.24 km/sec/Mpc. This is only slightly higher than the value of 70 used in many textbooks.

However, this only increases the gap between the value gained from this method and the value gained from the Planck telescope. Those experiments lead to a Hubble value of 66.53 km/sec/Mpc. This means the difference of a few hundred million years when calculating the age of the universe.

At this point, astronomers can only guess at the cause of the discrepancy. Many point fingers at Dark Energy or a fourth flavor of Neutrino, but ultimately we hope that the next generation of telescopes can show us the answers.

Source:
BBC News
arXiv

Double Black Hole Hails Discovery of Gravity Waves

Summary: It's the announcement of a discovery you didn't know you were waiting for. The detection of gravitational waves. It sounds weird, of course, but Einstein was onto something big when he was working on his theory of general relativity. Similar to a ball warping the surface of a rubber sheet, or a kayak being thrown into the water, large objects in outer space warp the fabric of the four dimensional spacetime that we live in.

When this happens, gravitational waves ripple through space and expand or contract the space around them. These waves have been undetectable until now. It is thanks to the LIGO interferometer that we can detect these faint waves in the universe. These waves are understandably hard to detect, the measurements are on a scale less than a width of an atom. They were able to detect this thanks to a double black hole.

Quite deservedly, the scientists involved are quite proud of their work. As this is both the first detection of gravity waves and the first direct detection of a black hole in addition to being confirmation of general relativity, they are confident that there is a Nobel Prize in their future and I am inclined to agree.

Either way, it is an exciting breakthrough in astronomy and one that I am excited to have as I enter the field.


APS Article
BBC News
Nature
SciShow

Landing a rocket

Summary: In case your Twitter feed was not just lighting up as much as mine was, Space X just made space history. In the upgrade to their Falcon 9 rocket, the booster did more than just separate, it landed itself back on earth, right where it was supposed to.

In a beautiful video, I just watched a great ball of fire slowly descend to the landing pad and then fade out to reveal a booster rocket standing as straight as you please. Absolutely incredible. The whole of mission control was throwing a party. 

The rest of the rocket went on to deploy six more satellites to complete the constellation arrangement. 

I'll update this post with a link to the video of the launch and further details as I get them.

SpaceX launch video (I suggest starting at about 21:00)
The above link will also give more mission details.

Background on the launch

Long exposure of the launch and landing of the rocket

    
The booster rocket safely on the landing pad

Strong Forces Between Antipotons

Summary: Woah, a story about antimatter on an antimatter blog! Finally.

Unlike a lot of other anitmatter and particle physics news, this does not come to us from CERN but rather from in Relativistic Heavy Ion Collider (RHIC) at Brookhaven in New York. Here physicists were able to measure the interactions between antiprotons. It seems like it is also the strong force, an attractive force, that holds the antiprotons together just as it also holds the protons together. This is just one more way in which protons and antiprotons are essentially the same, the exception of their opposite charge. Because of the similarity scientists can rule this out as a possible explanation for the matter/antimatter asymmetry in the universe today.

BBC News
Nature

Tractor Beams made of Sound

Summary: It may not be quite the tractor beam that you expect from a scifi show like "Star Trek," but we are getting closer. The way these scientists have developed relies on the pressure of sound waves. Instead of trying to create a concentrated beam that holds a particle, they instead create a vacuum of space, bounded by high intensity waves all around it. Then  by adjusting the boundaries, they are able to move the trapped particle. Currently the capabilities of the design only apply up to pea-sized particles at less than 40cm away.

Despite the apparent 3D nature of the holding pattern, it only requires a loudspeaker on one side of the particle. For the researchers, this means that it could be applied in the medical field for drug delivery. For those of us thinking of the future, this means that tractor beams on spaceships may be possible in a distant future. (Which the scientists did prove would work on a scaled down model.)


BBC News
Nature

Waters of Mars

Summary: As you have no doubt heard, NASA announced yesterday that there is now concrete evidence of flowing water on the surface of Mars. Amazing isn't it? I'll put a link to the press release but first let me highlight a few items. 

1. This was first noticed by am undergraduate student who was studying photos of the surface of Mars. They noticed that there were dark patterns on the surface, resembling river beds, that would appear in June and grow before shrinking again to nothing in September. They would then appear at the same time next year although never in the exact same spot. 

2. Not only was this proof of flowing liquid, but scientists were able to detect hydrated salt crystals. Proof that this liquid is definitely water. 

3. And because it is such a regular pattern, it is safe to assume that it has been occurring for much longer than five years. 

All this gives me greater hope for future exploration of Mars. Maybe this will provide enough public support that the space programs of the world can start collaborations more effectively. 

Of course the Whovian in me is also screaming that we shouldn't trust the water, but that's for another episode to address. 

NASA

Symmetry of Nuclei

Summary: Finally, some news about antimatter! Scientists at the LHC who are working on ALICE, have been able to more precisely measure the nuclei of particles and their antiparticles. Happily they discovered that there is fundamental symmetry with their charge, parity, and time.

The ALICE experiment smashes particles together that create nuclei and antinuclei at the same rate which allow the scientists to study them easier.


Quarks to Quasars
Nature

Another Nail in the Coffin for the Standard Model?

Summary: Data from the LHC's last run is still being analysed and with this comes possible new data to suggest faults in the standard model. Researchers at University of Maryland are studying leptons, subatomic particles that help to make up our universe. While studying the decay rate, they observed that not all particles decayed at the same rate as they should. Something was influencing the process.

What this mysterious force is, we do not know, but it is not predicted to exist in the standard model. This experiment is building on another experiment of their that also seemed to contradict the standard model. So it is not an instrumental error. Whatever it is, I am excited to find out.


RT
University of Maryland

Pluto Press Conference

Summary: It has been hard to miss the news of New Horizons flying past Pluto and getting beautiful images and data to send back to Earth. It has been harder to keep up with the constant flood of data that is pouring out. NASA has thankfully given a press conference and has published the highlights online.

Personally I am most overjoyed that they have nicknamed the dark spot on the top of Charon Mordor but I also love hearing about the giant ice cliffs. I will point you straight toward the mission site though to get all of the highlights.

If you have access to BBC, their program Sky at Night will be doing a big recap of all the news and what it means on the night of the 20th.


BBC News

Pluto through the years Credit: NASA

New particle seen at CERN

Summary: Nearly lost amid all the Pluto excitement, scientists at CERN have possibly discovered a new particle called the pentaquark. This new particle has been theorized to exist since the 60s and many have claimed to discover it before so they are being cautious. However, if this is indeed what is seems to be, then we have a new form of matter.

The pentaquark is a particle composed of four quarks and one antiquark.

Scientists found the particle by studying the way that the particle Lambda b decayed into three other particles. Some of the intermediary stages only made sense if the pentaquark did exist. Although still cautious about declaring this to be the pentaquark, the technology available to researchers at CERN allows them to view the problem in five dimensions rather than just one.

If this is indeed the particle they think it is, it will provide us with new ways of imagining quarks to be arranged and matter to be composed. Matter may be more complex than we thought.


BBC News

Quintuplet Stars

Summary: Our solar system features one star. There are many examples of binary star systems and even two binary stars coupled together. But astronomers have now found an incredibly rare new system. Two couples binary stars with one lonely companion star to make up a total of five stars.

Of the binaries, one is a detached pair and the other is coupled, meaning that the two stars share an outer atmosphere. Although there are no observations to prove it, it is possible that there are planets orbiting these stars. What a spectacular sky show they would have.


BBC News

Rise and Shine, Philae

Summary: Remember when there was a huge celebration because as a human race, we landed a rover on a comet? It was thrilling at the time, but we lost contact with the rover after it bounced into the shade of a cliff. Now the comet has tilted to allow sunlight to reach Philae and the rover has reached out to Earth.

A few very short message was received but it gives scientists hope and affirms that the rover may be able to still carry out its mission. There is not much else known at this point but the comet will be shifting into a position with more sunlight so more can be understood about the condition of the rover.


BBC News

LightSail Test Sucess

Summary: Launched on the 20th of May, the final step of preparation for the LightSail was launched. This was a test sail that would practice unfurling the sail and send back pictures to Earth. I am incredibly excited by this mission and have been ever since I saw the concept art nearly fifteen years ago as a possible design for futuristic spacecraft.

The LightSail is designed to work just like a sailboat; only instead of the wind filling the sail, it is light from the sun. Photons emitted from the sun will push the sail outward and the spacecraft will sail happily along. Even when it has passed beyond the reach of the sun's light, momentum will keep the craft going, even if not as fast.

This would not be a design intended for human travel since it is so slow, but more as a method of sending data gathering probes out into space with no power needed for propulsion beyond adjusting the sail. Furthermore, I believe this sail is not going to be able to tack and sail into the headwind. It will be a one-way mission.


Planetary Society