Day: December 20, 2016

A supermassive black hole (SMBH) is the largest type of black hole, on the order of hundreds of thousands to billions of solar masses (M☉), and is found in the center of almost all massive galaxies. In the case of the Milky Way, the SMBH corresponds with the location of Sagittarius A*.

Supermassive black holes have properties that distinguish them from lower-mass classifications. First, the average density of a supermassive black hole (defined as the mass of the black hole divided by the volume within its Schwarzschild radius) can be less than the density of water in the case of some supermassive black holes. This is because the Schwarzschild radius is directly proportional to mass, while density is inversely proportional to the volume. Since the volume of a spherical object (such as the event horizon of a non-rotating black hole) is directly proportional to the cube of the radius, the minimum density of a black hole is inversely proportional to the square of the mass, and thus higher mass black holes have lower average density. In addition, the tidal forces in the vicinity of the event horizon are significantly weaker for massive black holes. As with density, the tidal force on a body at the event horizon is inversely proportional to the square of the mass: a person on the surface of the Earth and one at the event horizon of a 10 million M☉ black hole experience about the same tidal force between their head and feet. Unlike with stellar mass black holes, one would not experience significant tidal force until very deep into the black hole.

Launched on Aug. 4, 2007, Phoenix landed on May 25, 2008, farther north than any previous spacecraft sent to Mars. The lander dug, scooped, baked, sniffed and tasted the Red Planet’s soil. Among early results, it verified the presence of water-ice in the Martian subsurface, which NASA’s Mars Odyssey orbiter first detected remotely in 2002. Phoenix’s cameras also returned more than 25,000 pictures from sweeping vistas to near the atomic level with the first atomic force microscope ever used outside Earth.

During its mission, Phoenix confirmed and examined patches of the widespread deposits of underground water ice detected by Odyssey and identified a mineral called calcium carbonate that suggested occasional presence of thawed water. The lander also found soil chemistry with significant implications for life and observed falling snow. The mission’s biggest surprise was the discovery of perchlorate, a chemical on Earth that is food for some microbes and potentially toxic for others.

“Phoenix not only met the tremendous challenge of landing safely, it accomplished scientific investigations on 149 of its 152 Martian days as a result of dedicated work by a talented team,” said Phoenix project manager Barry Goldstein at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

Additional findings included documenting a mildly alkaline soil environment unlike any found by earlier Mars missions; finding small concentrations of salts that could be nutrients for life; and discovering perchlorate salt, which has implications for ice and soil properties.

Phoenix’s findings also added to the history of water on Mars. These findings included excavating soil above the ice table, revealing at least two distinct types of ice deposits; observing snow descending from clouds; providing a mission-long weather record, with data on temperature, pressure, humidity and wind; observations of haze, clouds, frost and whirlwinds; and coordinating with NASA’s Mars Reconnaissance Orbiter to perform simultaneous ground and orbital observations of Martian weather.

How and when will the Universe end? Gravity and dark matter are poised to annihilate the Universe in a big crunch. Expansion and dark energy may tear it apart. Or, a phase transition could kill us tomorrow in a cosmic death bubble.

Pluto was discovered in 1930 by an astronomer from the United States. An astronomer is a person who studies stars and other objects in space.

Pluto was known as the smallest planet in the solar system and the ninth planet from the sun.

Today, Pluto is called a “dwarf planet.” A dwarf planet orbits the sun just like other planets, but it is smaller. A dwarf planet is so small it cannot clear other objects out of its path.

On average, Pluto is more than 3.6 billion miles (5.8 billion kilometers) away from the sun. That is about 40 times as far from the sun as Earth. Pluto orbits the sun in an oval like a racetrack. Because of its oval orbit, Pluto is sometimes closer to the sun than at other times. At its closest point to the sun Pluto is still billions of miles away.

Pluto is in a region called the Kuiper (KY-per) Belt. Thousands of small, icy objects like Pluto are in the Kuiper Belt.

Pluto is only 1,400 miles (2,300 kilometers) wide. That’s about half the width of the United States. Pluto is slightly smaller than Earth’s moon. It takes Pluto 248 years to go around the sun. One day on Pluto is about 6 1/2 days on Earth.

Pluto was named by an 11-year-old girl from England. The dwarf planet has five moons. Its largest moon is named Charon (KER-ən). Charon is about half the size of Pluto. Pluto’s four other moons are named Kerberos, Styx, Nix and Hydra.

The Hubble Space Telescope is one of the towering scientific and technological achievements of our age, and it has deepened our capacity for observation and discovery beyond measure. The documentary Hubble: Universe in Motion probes the revelations brought forth from this breathtaking invention, and celebrates its role in forever altering our understanding of the universe.

First launched into orbit in April of 1990, the Hubble telescope remains in operation to this day. It’s captured a series of beautiful and fascinating details which may hold the key to comprehending the mysteries of an evolving galaxy. Reaching depths and realms of space never before documented or even imagined, the Hubble has enabled top astronomers tremendous insights into the history and functions of solar systems, black holes, exploding stars, planets and even the possibility of inter-galactic life.

Hubble: Universe in Motion summarizes several of the most profound discoveries made possible by the Hubble. For example, the telescope has successfully traced the violent process of star formation, and offered clues relating to the course of each star’s entire life span. Armed with this knowledge, scientists can reasonably predict the future of our own Sun. In another segment of the film, we learn how the unparalleled resolution of Hubble telescope imagery has allowed astronomers the ability to pinpoint characteristics of the Milky Way and Andromeda galaxies in greater detail than ever before. They’ve also uncovered the existence of massive black holes residing in the center of the most active galaxies in the universe, examined the most obscure blemishes on Pluto’s surface, and basked in the awe-inspiring intricacies of Saturn’s majestic rings.

The documentary is populated by the gorgeous and revealing imagery captured by the Hubble telescope over the last quarter of a century. In that brief amount of time, the Hubble has answered many of the questions that have long plagued the most ardent astronomy enthusiasts, and inspired new queries that had not previously been considered. The film uses clear and crisp narration to explain complex scientific concepts, and offers precious insight into the origins of the universe and our place within it.