Friday, January 13, 2017

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

Wednesday, November 30, 2016

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

Saturday, September 24, 2016

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.

Thursday, September 8, 2016

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

Wednesday, June 15, 2016

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

Tuesday, June 7, 2016

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

Thursday, February 11, 2016

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