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

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.

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

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

The Case of the Strangled Galaxies

Summary: Galaxies are considered dead when they no longer are producing new stars. It is still unclear what causes this process but what astronomers do now know is the most common time scale of them dying -- approximately four billion years. Astronomers are calling this process strangulation.

Astronomers are able to tell how quickly the galaxy died based on the metal content remaining in the galaxy. The more stars that are being formed in a galaxy, the more metal content is seen. The way it works is simple. If a galaxy dies quickly and quite violently (for instance if the cool gas that fuels the star formation is suddenly ripped away), then the stars immediately stop producing and the metal content remains the same. But if the galaxy if cut off from the supply of cool gas but still continues to produce stars, using up the last of the supply, the metal content in the galaxy grows and grows until it "suffocates".

The difference was seen when comparing the spectra of light emitted by red, passive galaxies and blue, star-forming galaxies. With the data from Sloan they were able to see that the dead galaxies were, on average, four billion years older than the active galaxies. This is consistent with the amount of time the astronomers had calculated it would take to burn of the remaining amount of gas supply whilst strangling to death.

While the astronomers are now confident that death by strangulation is the most common way a galaxy meets it's ultimate end, it is still not clear what causes this. The most likely suspect at this point in time seems to be overcrowding which would lead to a greater probability of disruption to the gas supply, but this would need further investigation.



BBC News
Nature

Changing the Speed of Light

Summary: Scientists in Scotland have successfully altered the speed of light. Incredible in my humble opinion. To do this, they used a mask to alter the shape of a photon. This slowed the light down. Then the photon was released back into free space and raced against a photon of unaltered shape. Amazingly, the altered particle remained at the lower speed.

At this initial stage it is nothing more than a curiosity but it could have implications for astronomy. While it would not make a difference in small distances such as between Earth and the moon, if photons mutate shape in nature then our distances to far off stars and galaxies may not be as accurate as previously assumed.

BBC News

Astronomical Updates

Highest Quality image of Ceres:
Ceres, the 950-km wide dwarf planet has a new image that is clearer than ever before. The resolution beats that of Hubble's image of Ceres. The cool thing is the image quality can only improve as Dawn approaches.

BBC News


New Horizons setting it's sights on Pluto:
The New Horizons probe will be zooming by Pluto on July 14th of this year but before it reaches the planet, it must start taking images to calibrate it's instruments and check its trajectory. The first images, with Pluto only as a tiny speck, should be released this week. Researchers are hoping that this mission will reveal many surprises about Pluto including new moons and possible rings.

BBC News


Large Asteroid and it's Moon:
The asteroid 2004 BL 86 was seen with a moon as it passed relatively close to Earth. The asteroid itself is 325m wide and it's moon is 70m wide.

BBC News

Using the Eye of Sauron to see Great Distances

Summary: Two of my geeky obsessions have overlapped at long last. And in an exciting way too. As we strive to learn more about the beginnings of our universe, astronomers need new ways to measure distances to distant galaxies. The galaxy NGC4151, nicknamed The Eye of Sauron, has provided that.
The method relies on measuring the size of the supermassive black holes found at the center of all big galaxies. These black holes swallow up a huge about of gas and end up spewing emissions back out to become an AGN. The hot dust becomes a ring around the black hole which the astronomers used for measuring distance. By measuring the time delay between the emission of light from very close to the black hole and the infrared emission of the dust ring, we are able to know the distance the light has had to travel from the black hole to the ring.
Knowing the physical size and the apparent size of the ring means astronomers have a new method of measuring distance with only a 10% uncertainty. Not the most precise method we have but it is one that can be easily applied to many other galaxies out there.


AlphaGalileo
Nature

Lonely Stars

Summary: Two missions in 2010 and 2012 saw a rocket launched for a ten minute look at the Extragalactic Background Light (EBL) from above the atmosphere. What is the EBL? Professor Jaime Bock of JPL puts it this way: "It's very faint - but basically the spaces between the stars and galaxies aren't dark. And this is the total light made by stars and galaxies during cosmic history."

Having two separate data collecting missions that looked at different area of the sky allows the scientists to rule out fluctuations due to dust within our solar system. Even with this precaution, there was still extra light. The team believes that based on the brightness and blueness of the EBL, it shows that stars exist outside of galaxies. There might even be just as many stars outside galaxies as inside; it's that bright.

Of course other astronomers are skeptical of this conclusion. They concede it may be possible but are leaving their minds open for new and different possibilities.


BBC News
Science Mag

Backlog of Articles

I've been really busy with my studies but I have been still finding articles. These are no longer recent but for the sake of record keeping I would still like to post them on here for your reading pleasure.

Giant Black Hole at the Heart of a Dwarf Galaxy
Physics World

Leap Forward in Quantum Teleportation
Business Insider

First Images from India's spacecraft
BBC News

Complex Organic Molecules, Now Found in Space
BBC News

The Water-ice of Mercury
BBC News

Death Star Moon has confusing innards
BBC News

New Distance Record for Tractor Beams
BBC News

Water on a Neptune sized exoplanet
BBC News

India and US to collaborate on Mission
NASA

Hidden Valleys of the Moon
BBC News

Comets, Coming to a Printer Near You

Have you ever bemoaned your lack of a model of a comet? Feel your bedroom is incomplete without one? Worry no more; you can now 3D print your own. The ESA has released a model of Comet 67P/Churyumov-Gerasimenko, the duck shaped comet Rossetta will be Landing on.
BBC News

Nobel Prize to Blue LEDs
BBC News

Virtual Lunar Reality

Summary: Virtual reality games are cool, right? But what about using that technology to further education? Scientists at Carnegie Mellon University are creating a lunar robot that will do just that. Using Oculus Rift technology, the controller will be able to see what the robot is seeing. With the goggles on, the user can turn their head to control the robot's cams and experience the moon as if they were really there. While this could be great for education, a fleet of these paired with museums will do wonders for reigniting the joy and wonder of outer space for the next generation. Maybe it is this that will inspire a future starship captain.


BBC News

A Peek at the Earliest Stars

Summary: At the beginning of our universe, stars were not made of the same elements that they are today. Everything in the early universe was composed of completely hydrogen and helium. It is the very first stars that created the heavier elements like carbon, oxygen, and iron. The supernovae from these stars are what spread these elements throughout the rest of our universe. But what about these first stars that were formed before these heavy elements were common? Scientists have just maybe found some hints of these that confirm this theory. A team of astronomers has found one of these low-metallicity stars.

Using spectroscopy to look at the elements in the star with the Japanese Subaru telescope, the scientists noticed that some colors, visual representations of elements, were missing. It had very low levels of heavy metals.

With the available telescopes on earth, we cannot get much more than the barest hints of these early stars. We wait, instead, for the future and the James Webb Space Telescope to look back far into the past and help cement our current observations and find stars from even earlier times.


BBC News
Science Mag

The Secret of the Super Bright Supernova

Summary, almost four years ago, astronomers found a supernova, PS1-10afx, that was 30 times brighter than any other of it's class. They didn't see any abnormalities that would account of this huge magnitude difference and were confused. However, this mystery has now been solved. Then Dr Robert Quimby and his team had an idea that proved fruitful. They looked to see if we were seeing this supernova through a gravitational lens. As it turns out, there was an entire galaxy directly in from of the supernova that was bending the light around it and magnifying it. PS1-10afx is just a normal Type 1A supernova. 

This is will be useful knowledge for measuring cosmic distances since objects of known brightness like Type 1A supernovae are a good constant against which we can measure other objects in the night sky.


BBC News
Science

Infant Moon of Saturn

Summary: Hiding in the images of Saturn's outermost rings, a new moon is being formed. Or at least it looks like it might be a new moon. It's only a slight bump in the images but it does give hints of being a new moon. It's not inconceivable either. The rings are made up of many particles of ice and rock which can start to clump and form a new moon. While it has not been officially confirmed as the start of a new moon yet, the object has been nicknamed Peggy.

Astronomers hope that Cassini's final orbit in 2016 will be able to get higher quality images to verify if it is indeed the beginnings of a new moon. If so, we then just have to cross our fingers to see if it will survive it's infancy. If it stays within the rings, it will have a constant barrage or rocks that could break it apart while it is still forming. If it moves out beyond the rings, Peggy will have to dodge the larger moons.

Even if it does not end up becoming a fully fledged moon, it is still a great opportunity to observe the creation of a new celestial object.

BBC News

Two New Discoveries in the Solar System

There's not too much to say about these. The first one is an asteroid that has been discovered to have it's own rings. This is the first asteroid we have found that has its own ring system.

BBC News
Nature


The second one is a new dwarf planet that has been discovered outside of Pluto's orbit. There's two main theories on its formation, but it has still yet to be officially confirmed.

BBC News
Nature

Cosmic Waves of Discovery

Summary: Scientists at the BICEP2 collaboration at the South Pole have detected signal that confirm theories of the rapid expansion of the universe immediately after the big bang. If validated by other experiments (which is likely to happen as the signal found is actually stronger than predicted) this confirms a super-rapid expansion within the first instants of the universe before "slowing down" to rapid expansion. What they found were twists in Cosmic Radiation Background that could have only been produced by gravitational waves.

So what does this mean? These signals tell astronomers that gravity was present during this time in which quantum effects dominated the, then very tiny, universe. This gives us greater hope that the Four Fundamental Forces can be one day combined into a unified Theory of Everything which could better describe conditions at the big bang.


BBC News
Minute Physics video explaining the discovery
Discussion on background and implications
Video of the founding scientists hearing the news
SciShow

The Future of African Astronomy

Summary: Due to a new radio telescope array in Africa, scientists are predicting a burst of enthusiasm for my favorite branch of physics. Right now, the challenge is to nurture the African scientists and make sure it is not just a flood of US scientists who happen to be in Africa. A long-term relationship with the country needs to be built up. South Africa is also hoping to use this project to inspire future generations of scientists in their country to boost their country's economy and world standing.

The telescope array will contain 3,000 radio dishes and will be able to scan the sky faster than any previous instruments of the kind. The headquarters of this project is in South Africa who took the other countries by surprise when they won the bid. They won the scientific community with clear skies and legislation that strictly limits the amount of radio noise in that area surrounding the telescope which will make the data incredibly accurate and meaningful.


Nature
Square Kilometer Array (SKA)

New 1% Accuracy of Universe

Summary:  Set by the Baryon Oscillation Spectroscopic Survey (BOSS), astronomers now have a new standard for measuring distances in the universe. Using baryon acoustic oscillations (BAOs), they have created a standard ruler of half a billion light years long which they can use to measure distances in the universe to a 1% accuracy.
With incredibly accurate measurements, astronomers can calibrate fundamental cosmological properties that were wishy-washy at best before. The most exciting one for me, is being able to pin down how dark energy accelerates the expansion of the universe. It also can help provide a better estimate of the curvature of the universe. The latest estimates of which, seem to indicate that the universe is flatter than we previously thought. If it gets much flatter, we may find out we are living in an infinite universe.


BBC News