Christine the Astrophysicist

[christinetheastrophysicist]

Two New Moons for Jupiter 

With the addition of two newly discovered moons, Jupiter is now home to 69 known satellites. The new moons, S/2016 J 1 and S/2017 J 1, were announced through the Minor Planet Electronic Circulars on June 2nd and June 5th, respectively.

S/2016 J 1 was discovered on March 8, 2016 at the Las Campanas Observatory in Chile. The moon orbits far from Jupiter, at an average distance of 20,600,000 km and taking 1.65 years to orbit the planet.

The other moon, S/2017 J 1, was discovered on March 23, 2017 at the Cerro Tololo Inter-American Observatory, also in Chile. It orbits further than the other moon at 23,500,000 km every 2.01 years.

Just like most of Jupiter's moons, these two have retrograde orbits, meaning they move in the opposite direction that Jupiter spins. It is believed that satellites with retrograde orbits were formed elsewhere in the Solar System and have been captured by the planet's gravity when passing by.

Images: The discovery images of the new Jovian satellites S/2016 J 1 (left) and S/2017 J 1 (right). Credit: Scott Sheppard

[christinetheastrophysicist]

New Craters on the Moon 

Impact craters are important features of planetary bodies, as they are the most dominant feature shaping their surfaces. Many planetary bodies are covered in them, such as Mercury and the Moon, while some show little signs of craters, such as Earth, due to active geological processes.

For a while, it was thought that significant changes to the Moon's surface took hundreds, maybe millions of years. The image above is one of many taken by the Lunar Reconnaissance Orbiter (LRO) that shows that the Moon's surface is changing, and much faster than previously thought.

During the LRO mission, 222 impact craters have been identified from pairs of before and after images. These new craters, the largest being 43 meters in diameter, are spread across the Moon's surface. Characteristics about these craters such as their size and the time between images can be used to determine the ages of various regions on the Moon's surface.

Image: Before and after of a new impact crater. (Credit: NASA/GSFC/Arizona State University)

[christinetheastrophysicist]

2016 marks the 25th anniversary of the first issue of JGR: Planets. We are marking this occasion with a collection of review papers focused on enduring and fundamental themes in planetary science that have framed the past quarter century and will strongly influence research and exploration in the next quarter century. With topics covering bodies small and large, processes on and in solid planets and giant planets, in atmospheres, and around other stars, this collection samples the broad scope of planetary science and of JGR: Planets.

[s-c-i-guy]

The Nobel Prize in Physics 2016 – David J. Thouless, F. Duncan M. Haldane, J. Michael Kosterlitz – “for theoretical discoveries of topological phase transitions and topological phases of matter”

They revealed the secrets of exotic matter

This year’s Laureates opened the door on an unknown world where matter can assume strange states. They have used advanced mathematical methods to study unusual phases, or states, of matter, such as superconductors, superfluids or thin magnetic films. Thanks to their pioneering work, the hunt is now on for new and exotic phases of matter. Many people are hopeful of future applications in both materials science and electronics.

The three Laureates’ use of topological concepts in physics was decisive for their discoveries. Topology is a branch of mathematics that describes properties that only change step-wise. Using topology as a tool, they were able to astound the experts. In the early 1970s, Michael Kosterlitz and David Thouless overturned the then current theory that superconductivity or suprafluidity could not occur in thin layers. They demonstrated that superconductivity could occur at low temperatures and also explained the mechanism, phase transition, that makes superconductivity disappear at higher temperatures.

In the 1980s, Thouless was able to explain a previous experiment with very thin electrically conducting layers in which conductance was precisely measured as integer steps. He showed that these integers were topological in their nature. At around the same time, Duncan Haldane discovered how topological concepts can be used to understand the properties of chains of small magnets found in some materials.

We now know of many topological phases, not only in thin layers and threads, but also in ordinary three-dimensional materials. Over the last decade, this area has boosted frontline research in condensed matter physics, not least because of the hope that topological materials could be used in new generations of electronics and superconductors, or in future quantum computers. Current research is revealing the secrets of matter in the exotic worlds discovered by this year’s Nobel Laureates.

[houghtonlib]

Galileo didn’t know it at the time, but his observations of sunspot activity in 1612 were tailor-made for the animated GIF! He demonstrated that sunspots can be tracked across the disk of the sun as it rotates–look for the cluster labeled R moving from top left to lower right.

Galilei, Galileo, 1564-1642. Istoria e dimostrazioni intorno alle macchie solari e loro accidenti, 1613.

*IC6.G1333.613ia 

Houghton Library, Harvard University

[sovietpostcards]

Rare Yuri Gagarin postcards that were published in Soviet Union in 1961 by small printshops.

[sagansense]

@yurisnight @YurisNight @Crowd2Space #crowd2space #yurisnight

[christinetheastrophysicist]

These slides, presented during the New Horizons' press conference at the 47th Lunar and Planetary Science Conference, show the climate zones of Pluto compared to Earth. Pluto has an axial tilt of 120°, which creates extreme tropic and arctic regions. The two regions overlap, creating a 'tropical arctic' region that experiences both direct sunlight and prolonged sunlight and darkness. At the moment, Pluto is in an intermediate state between the extreme tropic and arctic climates.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

[christinetheastrophysicist]

This image, taken by Panagiotis Xipteras, shows the visual double star Castor, the second brightest star in the Gemini constellation. Even though it appears to be a binary star, Castor is in fact a complex multi-star system composed of six stars. The primary stars, Castor A and B, are both A-type main sequence stars, whereas the third star, Castor C, is a BY Draconis variable star. Each one of these stars is accompanied by a red dwarf flare star.

Image: Castor captured with an iPhone 5s. (Credit: Panagiotis Xipteras)

[christinetheastrophysicist]

A Possible Impact on Jupiter?

In the last few days, a couple of videos were uploaded to YouTube, and tweeted about, of a possible impact on Jupiter. According to the observers, the possible impact occurred on March 17 at 00:18:33 UTC. It may or may not be something interesting, but hopefully more information will become available soon.

Below are the videos: Video 1 Video 2

[christinetheastrophysicist]

Dione’s Icy Mystery 

The Sidera Lodoicea are four of Saturn’s moons discovered by Giovanni Domenico Cassini at the Paris Observatory. Sidera Lodoicea translates to Louisian Stars, named in honor of King Louis XIV of France. One of the moons, Dione, has interesting thin, white bands on its surface that are highly reflective. When first photographed by Voyager, it was hypothesized that Dione was geologically active, possibly from cryovolcanism, or ice volcanoes, causing surface cracks to erupt. Closeup images of Dione from Cassini proved that hypothesis wrong and revealed that these features are actually cliffs of ice created by tectonic fractures.

Image: Dione's ice cliffs seen from Cassini. (Credit: NASA/JPL-Caltech/Space Science Institute)

[christinetheastrophysicist]

Comet Catalina Through Space 

This is a series of images featuring Comet Catalina, formally known as C/2013 US10. This 16-image GIF was compiled by Yasushi Aoshima and shows the comet from Shizuoka, Japan between 14:29 UT and 20:40 UT on January 16, 2016.

Comet Catalina was discovered by the Catalina Sky Survey in October 2013 and is classified as an Oort cloud comet. The bright blue area around the comet’s nucleus is a region of gas and dust called the coma. Behind the comet are its two tails. Pointing upwards is the ion tail and towards the bottom right is the dust tail. The ion tail points in the direction of the solar wind, while the dust tail follows behind the comet.

Image Credit: Yasushi Aoshima

[christinetheastrophysicist]

The Importance of Gravitational Waves 

On the morning of September 14, 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO), twin detectors located in Louisiana and Washington state, observed signals of ripples in spacetime. Also called gravitational waves, LIGO physicists have concluded that the waves were produced by the merger of two black holes.

By analyzing the signals, it is estimated that the two black holes had a mass 29 and 36 times greater than the Sun and is located 1.3 billion light years away. Based on the small time difference between the two detectors, it was determined that the source is located in the southern hemisphere in the direction of the Magellanic clouds.

100 years ago, Albert Einstein predicted the existence of gravitational waves with his theory of general relativity. In the 1970s and 80s, Joseph Taylor, Jr. and colleagues demonstrated the existence of gravitational waves through the discovery and observation of a pulsar-neutron star binary system.

Gravitational waves are important for studying regions of space that electromagnetic waves cannot reach. Such regions include, but are not limited to, the horizon of a black hole and the early moments of the Universe.

If you missed the announcement, there are press releases from LIGO, NASA, CalTech, and the media. The press conference is available on YouTube. The discovery was accepted for publication in the Physical Review Letters journal and a repository of other papers are available from LIGO. If you enjoy coding, there is an iPython notebook about signal processing with open data from LIGO.

Image: The plots show the signals recieved by each dectector, along with what is predicted by general relativity. The observed signals closely match the predictions. (Credit: LIGO)

[startalkradio]

Edgar Mitchell, the 6th man to walk on the moon, passed away Thursday night, at the age of 85. Mitchell was part of the Apollo 14 crew. Our thoughts go out to his family.

[christinetheastrophysicist]

The Changing Size of Jupiter 

Above is a series of images of Jupiter taken by NASA’s Pioneer 10 spacecraft. Jupiter appears as a crescent during the spacecraft’s approach, then gradually decreasing in size as Pioneer 10 continued past the Jovian system.

Pioneer 10 was the first spacecraft to visit Jupiter in 1973. After Jupiter, it continued through the orbits of the other outer planets. The Pioneer 10 mission ended in 1997, with communications continuing until a final, faint signal was received in 2003. Pioneer 10 is traveling towards Aldebaran, an orange giant star in the constellation Taurus, and will make its closest approach in about 2 million years.

Image Credit: NASA

[christinetheastrophysicist]

Hubble’s Legacy 

Title: First Results from the Hubble OPAL Program: Jupiter in 2015

Authors: A. A. Simon, M. H. Wong, G. S. Orton

For the remainder of Hubble’s lifetime, the Hubble 2020 Outer Planet Atmospheres Legacy (OPAL) program will produce new global maps of the giant planets every year. Hubble’s Wide Field Camera 3 (WFC3) will be used to observe the atmospheric phenomena of each planet, such as storm activity and aerosol distributions.

The program began by observing Jupiter during Hubble’s cycle 22, occurring between October 2014 and September 2015. In order to produce a global map of Jupiter, Hubble needs to complete 6-7 consecutive orbits, where each orbit provides about 52 minutes of visibility. All images were acquired with the Ultraviolet Imaging Spectrograph (UVIS) detector, making use of different filters to allow for a variety of features to become visible.

The data provides insight into many of Jupiter's atmospheric features. Jupiter's zonal wind flow, wind moving along latitudinal lines, or the west-east direction, were found to be similar to data obtained by the Voyager and Cassini missions. A feature not seen before in previous Hubble data is a small wave in the North Equatorial Belt (NEB), a region that is home to many small cyclonic cells. This particular wave feature is reminiscent of a baroclinic wave, which is responsible for shaping cyclones on Earth.

Jupiter’s most prominent feature, the Great Red Spot (GRS), is still orange. Another of Jupiter’s features, Oval BA, located southeast of the GRS, appears paler in color. Imaging in the violet wavelengths shows that the interior of the GRS is gradually shrinking.

Even though the program has just begun, the new Jupiter data has already been producing interesting results. The OPAL program will continue to study the giant planets for the remainder of Hubble’s and its camera’s lifetimes.

Image: Projections of the first two Jupiter rotations. This image is a combination of three Hubble filters. (Credit: Simon et al.)

[christinetheastrophysicist]

If you have been following astronomy news today, you probably saw a lot of talk about a ninth planet in our solar system. Caltech astronomers Konstantin Batygin and Mike Brown have used mathematical modeling and computer simulations to show that a planet-sized object could exist in the outer solar system and that this object could be influencing the elongated orbits of Sedna-like bodies.

This planet would be about 10 times the mass of the Earth and 20 times farther from the Sun than Neptune. At this distance, the planet would take between 10,000 and 20,000 years to complete one orbit.

This paper is free for 30 days, so if you want to look at it, you better get it now. Keep in mind that this is a prediction of a new planet, NOT the discovery of one.

Happy reading!

[christinetheastrophysicist]

Goldilocks Planets, Visualized 

This interactive visualization, created by Jan Willem Tulp, shows all of the known exoplanets that reside in the Goldilocks Zone, the region around a star where liquid water could exist. In addition to showing the exoplanets that reside in the habitable zone, this visualization explores their similarity to Earth, their composition, atmosphere, mass, and temperature, as well as the amount of energy that they receive from their host star.

This visualization is hosted at goldilocks.info. The data is retrieved from the Planetary Habitability Lab at the University of Puerto Rico at Arecibo.