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Habitable, Earth-like planets can form even after giant planets have barrelled through their birthplace on epic migrations towards their host stars, new computer simulations suggest. The finding contradicts early ideas of how planets behave and suggests future space missions should search for terrestrial planets near known "hot Jupiters". Many of the 160 or so known extrasolar planets are hot Jupiters - massive planets that are closer to their stars than Mercury is to our Sun. But the planets probably did not form in these scorching regions because there would not have been enough gas and dust there to amass such...

Early in our own solar system's history, the largest of these planetary embryos acquired a dense envelope of hydrogen and helium and transformed into the gas giants we know today... Planets that form far from their parent star are expected to have a composition similar to comets (50% rock, 50% water by weight). Once a planet exceeds about ten Earth masses it has enough gravity to attract any hydrogen and helium near its orbit, and will rapidly transform into a gas giant... [A planet] in this region that never exceed the threshold... becomes an "ocean planet", a term coined by...

Paris (AFP) - The Solar System has at least two more planets waiting to be discovered beyond the orbit of Pluto, Spanish and British astronomers say. The official list of planets in our star system runs to eight, with gas giant Neptune the outermost. Beyond Neptune, Pluto was relegated to the status of "dwarf planet" by the International Astronomical Union in 2006, although it is still championed by some as the most distant planet from the Sun. In a study published in the latest issue of the British journal Monthly Notices of the Royal Astronomical Society, researchers propose that "at...

Neptune’s moons are ...all are named for gods of the sea, or for the children of Poseidon (which include Triton, Proteus, Depsina and Thalassa), minor Greek water dieties (Naiad and Nereid) or Nereids , the water nymphs in Greek mythology (Halimede, Galatea, Neso, Sao, Laomedeia and Psamathe). Neptune’s Regular Moons are those located closest to the planet and which follow circular prograde orbits that lie in the planet’s equatorial plane. They are, in order of distance from Neptune: Naiad , Thalassa , Despina, Galatea, Larissa , S/2004 N 1, and Proteus. All but the outer two are within Neptune-synchronous orbit......

From the start, Sedna was an odd-ball. Its 11,400 year orbit takes it from a perihelion of 76 astronomical units (for context, Neptune is an average of 30 AUs from the Sun) to an amazing 936 AUs from the Sun. (A thousand AUs is 1.6% of a light year, and 0.4% of the way to Proxima Centauri, the closest star to our solar system). Currently at a distance of 86 AU and headed towards perihelion in 2076, we’re lucky we caught Sedna as it ‘neared’ (we use the term ‘near’ loosely in this case!) the Sun. But this strange path...

The planets of the outer Solar System are known for being strange, as are their many moons. This is especially true of Triton, Neptune’s largest moon. In addition to being the seventh-largest moon in the Solar System, it is also the only major moon that has a retrograde orbit – i.e. it revolves in the direction opposite to the planet’s rotation. This suggests that Triton did not form in orbit around Neptune, but is a cosmic visitor that passed by one day and decided to stay. ... Triton has a radius, density (2.061 g/cm3), temperature and chemical composition similar to...

ASBURY PARK — Fueled by a child custody dispute, a recently divorced Neptune Township police officer shot and killed his former wife in broad daylight on Tuesday in front of their daughter on an Asbury Park street, authorities said. *** While taking him into custody, some of the officers hugged him and patted him comfortingly on the back, the witness said.

In July, New Horizons crosses the next great frontier in our solar system. Mankind is about to visit one of the strangest places in our solar system. Out beyond Neptune, the Kuiper belt is home to hordes of cold, lumpy worlds -- some of which are large enough to have their own moons, but none of which we've seen up-close before. That's going to change this summer, when NASA's New Horizons spacecraft flies by "the king of the Kuiper belt": Pluto. It's no longer considered a planet, but Pluto is still an important member of our solar system, and one...

Explanation: Two hours before closest approach to Neptune in 1989, the Voyager 2 robot spacecraft snapped this picture. Clearly visible for the first time were long light-colored cirrus-type clouds floating high in Neptune's atmosphere. Shadows of these clouds can even be seen on lower cloud decks. Most of Neptune's atmosphere is made of hydrogen and helium, which is invisible. Neptune's blue color therefore comes from smaller amounts of atmospheric methane, which preferentially absorbs red light. Neptune has the fastest winds in the Solar System, with gusts reaching 2000 kilometers per hour. Speculation holds that diamonds may be created in the...

Explanation: On another Valentine's Day 25 years ago, cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back one last time to make this first ever Solar System family portrait. The complete portrait is a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane. In it, Voyager's wide angle camera frames sweep through the inner Solar System at the left, linking up with gas giant Neptune, the Solar System's outermost planet, at the far right. Positions for Venus, Earth, Jupiter, Saturn, Uranus, and Neptune are indicated by letters, while the Sun is...

While asteroids residing in the inner solar system will pass quickly through such small fields, trans-Neptunian objects (TNOs) orbit the Sun much more slowly. For example, Pluto, at an approximate distance of 40 A.U. from the Sun, along with the object Eris, presently the largest of the TNOs, has an apparent motion of about 27 arc seconds per day – although for a half year, the Earth’s orbital motion slows and retrogrades Pluto’s apparent motion. The 27 arc seconds is approximately 1/60th the width of a full Moon. So, from one night to the next, TNOs can travel as much...

Explanation: What would it look like to fly past Triton, the largest moon of planet Neptune? Only one spacecraft has ever done this -- and now, for the first time, images of this dramatic encounter have been gathered into a movie. On 1989 August 25, the Voyager 2 spacecraft shot through the Neptune system with cameras blazing. Triton is slightly smaller than Earth's Moon but has ice volcanoes and a surface rich in frozen nitrogen. The first sequence in the video shows Voyager's approach to Triton, which, despite its unusual green tint, appears in approximately true color. The mysterious terrain...

Explanation: Cruising through the outer solar system, the Voyager 2 spacecraft made its closest approach to Neptune on August 25, 1989, the only spacecraft to visit the most distant gas giant. Based on the images recorded during its close encounter and in the following days, this inspired composited scene covers the dim outer planet, largest moon Triton, and faint system of rings. From just beyond Neptune's orbit, the interplanetary perspective looks back toward the Sun, capturing the planet and Triton as thin sunlit crescents. Cirrus clouds and a dark band circle Neptune's south polar region, with a cloudy vortex above...

Scientists using data from NASA's Wide-field Infrared Survey Explorer, or WISE, have uncovered new clues in the ongoing mystery of the Jovian Trojans -- asteroids that orbit the sun on the same path as Jupiter. Like racehorses, the asteroids travel in packs, with one group leading the way in front of the gas giant, and a second group trailing behind. The observations are the first to get a detailed look at the Trojans' colors: both the leading and trailing packs are made up of predominantly dark, reddish rocks with a matte, non-reflecting surface. What's more, the data verify the previous...

Small objects could be rounded worlds, based on likely sizes, experts say. Three relatively bright space rocks recently found in Pluto's neighborhood may be new members of the dwarf planet family, astronomers say. The objects were discovered in a little studied section of the Kuiper belt, a region of the solar system that starts beyond the orbit of Neptune and extends 5.1 billion miles (8.2 billion kilometers) from the sun. Astronomer Scott Sheppard, of the Carnegie Institute of Washington, and colleagues found the bodies using the 1.3-meter Warsaw University Telescope at Las Campanas in Chile. The region of the Kuiper...

A theory is hereby proposed that an unknown mega-massive planet has, for billions of years, been orbiting at 77.2 AU from the sun -- within a 44 AU-wide, virtually empty Great Void that surrounds the Kuiper Belt (One AU = 93 million miles, the mean Earth-Sun distance). The Void is postulated to have been formed by strong gravitational attraction of the unknown planet having removed all CKBOs (Classical Kuiper Belt Objects) that had existed previously in the vicinity of the massive planet's huge orbit... The 77.2 AU distance from the sun of the proposed unknown planet is derived from a...

Beyond Neptune lies a reservoir of... icy debris left to roam the solar system's dim outer limits having never coalesced into planets... Named for astronomer Gerard Kuiper, who in 1951 predicted the existence of this 3-billion-kilometer-wide swath of icy chunks, the Kuiper belt didn't begin to reveal itself to observers until 1992. Since then, researchers have found more than a thousand bodies filling a doughnut-shaped belt, which extends 30 to about 50 astronomical units from the sun. One astronomical unit is the average distance between the Earth and sun... The puffed-up, elongated orbits and present-day sparseness of the belt all...

Many of the primitive bodies wandering the asteroid belt between Mars and Jupiter are former comets, tossed out of orbit by a brutal ballet between the giant outer planets, said a team of astrophysicists. A commonly accepted theory is that the asteroid belt is the rubble left over from a "proto-planetary disk," the dense ring of gas that surrounds a new-born star. But the orbiting rocks have long been a source of deep curiosity. They are remarkably varied, ranging from mixtures of ice and rock to igneous rocks, which implies they have jumbled origins. The answer to the mystery, according...

...the planets weren't always in the order they are today. Four billion years ago, early in the solar system's evolution, Uranus and Neptune switched places. This is the result of recent work by Steve Desch, assistant professor in the School of Earth and Space Exploration at Arizona State University. The work appears in this week's Astrophysical Journal. Desch based his conclusion on his calculations of the surface density of the solar nebula. The solar nebula is the disk of gas and dust out of which all of the planets formed. The surface density -- or mass per area -- of...

Explanation: Despina is a tiny moon of Neptune. A mere 148 kilometers across, diminutive Despina was discovered in 1989, in images from the Voyager 2 spacecraft taken during its encounter with the solar system's most distant gas giant planet. But looking through the Voyager 2 data 20 years later, amateur image processor and philosophy professor Ted Stryk discovered something no one had recognized before -- images that show the shadow of Despina in transit across Neptune's blue cloud tops. His composite view of Despina and its shadow is composed of four archival frames taken on August 24, 1989, separated by...