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From an article published on September 30, 2015 at www.space.com:

www.space.com

Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Colorful new maps of Ceres, charted by NASA’s Dawn space probe, have been unveiled at the European Planetary Science Conference in France. The maps highlight the dwarf planet’s topography and composition, as well as a pyramid-shaped mountain and the Occator crater, where many mysterious bright spots can be found.

Dawn scientists are also discussing three bursts of energetic electrons that have them puzzled. As Dawn principal investigator Chris Russell put it, “Ceres continues to amaze”.

To learn more about the outer Solar System, see Chapter 8 of The Cosmos.

Link to the full article on www.space.com

From an article on the American Scientist website:

Debra Fischer is an astrophysicist at Yale University who has discovered hundreds of exoplanets, and she was the first to discover a system with several exoplanets around one star.

On September 30, American Scientist met up with Dr. Fischer for a Google Hangout to discuss the methods used to find exoplanets, how much we can currently decipher about these planets’ properties, and what new information some planned ground and space-based observatories might be able to contribute. She also tackled the all-important question of whether we might find exoplanets that support life.

This event marked the first in a series of Google Hangouts with all of Sigma Xi’s Distinguished Lecturers, one of whom is Dr. Fischer. Dr. Fischer also helps to run a citizen science project called Planet Hunters, which aims to classify readings and find exoplanets with the public’s help.

For an in-depth discussion on exoplanets and how they are discovered, see Section 9.2, p. 236-244 in The Cosmos.

Link: Original article on American Scientist

Our Solar System seems like a neat and orderly place, with small, rocky worlds near the Sun and big, gaseous worlds farther out, all eight planets following orbital paths unchanged since they formed. However, the true history of the Solar System is far more riotous. Giant planets migrated in and out, tossing interplanetary flotsam and jetsam far and wide.

New clues to this tumultuous past come from the asteroid belt. Millions of asteroids circle the Sun between the orbits of Mars and Jupiter, in a region known as the main asteroid belt. Traditionally, they were viewed as the pieces of a failed planet that was prevented from forming by the influence of Jupiter’s powerful gravity. Their compositions seemed to vary methodically from drier to wetter, due to the drop in temperature as you move away from the Sun.

base

Credit: David A. Aguilar (CfA)

This traditional view has changed, as astronomers have recognized that the current residents of the main asteroid belt weren’t all there from the start. In the early history of the Solar System the giant planets ran amok, migrating inward and outward substantially. Jupiter may have moved as close to the Sun as Mars is now. In the process, it swept the asteroid belt nearly clean, leaving only a tenth of one percent of its original population. As the planets migrated, they stirred the contents of the Solar System. Objects from as close to the Sun as Mercury, and as far out as Neptune, all collected in the main asteroid belt.

Using data from the Sloan Digital Sky Survey, astronomers have examined the compositions of thousands of asteroids within the main belt. They found that the asteroid belt is more diverse than previously realized, especially when you look at the smaller asteroids. This finding has interesting implications for the history of Earth. Astronomers have theorized that long-ago asteroid impacts delivered much of the water now filling Earth’s oceans. If true, the stirring provided by migrating planets may have been essential to bringing those asteroids.

This raises the question of whether an Earth-like exoplanet would also require a rain of asteroids to bring water and make it habitable. If so, then Earth-like worlds might be rarer than we thought.  The paper describing these findings appears in the January 30, 2014 issue of Nature.

Links: Harvard-Smithsonian Center for Astrophysics press release; Nature article.

In this short article for The Conversation, Helen Maynard-Casely summarizes current efforts in exploring the Solar System, with missions underway to nearly every planet (and dwarf planet, Pluto).

Astronomers have used data from the Spitzer Space Telescope to measure the distances, and hence temperatures, of so-called “brown dwarfs” (see Section 9.5).

These brown dwarfs, the coldest known free-floating celestial bodies, were found to be warmer than previously thought, with surface temperatures ranging from about 250 to 350 degrees Fahrenheit (125 to 175 degrees Celsius). By comparison, the Sun has a surface temperature of about 10,000 degrees Fahrenheit (around 6000 degrees Celsius).

To reach these surface temperatures after cooling for billions of years, these objects would have to have masses of only 5 to 20 times that of Jupiter. Unlike the Sun, the only source of energy for these coldest of brown dwarfs is from their gravitational contraction, which depends directly on their mass. The Sun is powered by the conversion of hydrogen to helium; these brown dwarfs are not hot enough for this type of “nuclear burning” to occur.

PIA17258_ip

Credit: NASA/JPL-Caltech

The findings help researchers understand how planets and stars form, but also present new puzzles to astronomers who study cool, planet-like atmospheres, as the observable properties don’t correlate with temperature in a straight-forward way. Ongoing studies of newly discovered brown dwarfs may shed some light (and heat) on these outstanding issues.

Read the JPL press release for more detail and additional images.