Free Republic

A size comparison of the planets of the TRAPPIST-1 system, lined up in order of increasing distance from their host star. The planetary surfaces are portrayed with an artist’s impression of their potential surface features, including water, ice, and atmospheres. Amy Barr's paper “Interior Structures and Tidal Heating in the TRAPPIST-1 Planets” shows that planets d and e are the most likely to be habitable due to their moderate surface temperatures, modest amounts of tidal heating, and because their heat fluxes are low enough to avoid entering a runaway greenhouse state. Planet d is likely covered by a global water...

The most massive galaxies in our neighbourhood formed their stars billions of years ago, early in the history of the universe. At the present day, they produce very few new stars. Astronomers have long believed that is because they contain very little gas – a key ingredient necessary to produce stars. But our new study, published in Nature Astronomy, is now challenging this long held view. Through probing the extreme environments of faraway massive galaxies, we can learn not only about their evolution and the history of the universe, but most importantly about the fundamental processes regulating the formation of...

New work probes the extraterrestrial source of incredibly powerful explosions of radio waves, investigating why that spot is the only known location to repeatedly burst with these blasts.  These repeating bursts may come from a dense stellar core called a neutron star near an extraordinarily powerful magnetic field, such as one near a massive black hole, the study finds. Fast radio bursts, or FRBs, are intense pulses of radio waves lasting just milliseconds that can give off more energy in a fraction of a second than the sun does in hours, days or weeks. FRBs were discovered only in 2007,...

A new study using data from NASA's Kepler Space Telescope shows that in most cases, exoplanets orbiting the same star have similar sizes and regular spacing between their orbits.  By contrast, our own solar system has a range of planetary sizes and distances between neighbors. The smallest planet, Mercury, is about one-third the size of Earth — and the biggest planet, Jupiter, is roughly 11 times the diameter of Earth. There also are very different spacings between individual planets, particularly the inner planets.  This means our solar system may have formed differently than other solar systems did, the research team...

The Plasma Magnet Drive: A Simple, Cheap Drive for the Solar System and Beyondby Paul Gilsteron December 29, 2017 Can we use the outflow of particles from the Sun to drive spacecraft, helping us build the Solar System infrastructure we’ll one day use as the base for deeper journeys into the cosmos? Jeff Greason, chairman of the board of the Tau Zero Foundation, presented his take on the idea at the recent Tennessee Valley Interstellar Workshop. The concept captured the attention of Centauri Dreams regular Alex Tolley, who here analyzes the notion, explains its differences from the conventional magnetic sail,...

================================================================================================================ Researchers have re-examined data captured by the Voyager 2 spacecraft back in 1986, and think they've found evidence of two never-before-seen moons hidden in the rings of Uranus. Uranus, the third largest planet in our Solar System, already has 27 moons that we know of - but these two new ones appear to orbit the planet more closely than any of its other natural satellites, and are causing wavy patterns in its closest rings. Although Saturn is the most famous ringed planet orbiting our Sun, it's not the only one, with the three other gas giants - Jupiter, Uranus,...

There may be small, rocky planets in the nearby Alpha Centauri triple-star system that have been overlooked, according to a new study published in the Astronomical Journal Alpha Centauri, also known as Rigil Kentaurus, Rigil Kent and Gliese 559, is the closest stellar system to Earth. This triple system is made up of the bright binary star formed by Alpha Centauri A and B, plus the faint red dwarf star Alpha Centauri C. The two brighter components are roughly 4.35 light-years away from us. Alpha Centauri C, better known as Proxima Centauri, is slightly closer, at 4.23 light-years. Compared to...

A leading astronomer studying the origins of the space object known as Oumuamua has come out declaring it’s an alien probe with broken engines. Dr. Jason Wright claims that Oumuamua’s movement is that of a craft that has lost power to its engines. Right now, leading scientists are studying the odd “cigar-shaped” object which originated outside of our solar system. Teams lead by renowned physicist, Stephen Hawking, are attempting to discover whether or not Oumuamua is alien or natural. If a radio signal is detected later today, scientists will “proceed with caution.” Professor Avi Loeb, Professor of Astronomy at Harvard...

Astronomers are set to scan an 'alien' comet for signs of extraterrestrial signals The cigar-shaped object, named 'Oumuamua, sailed past Earth last month The mysterious comet is the first interstellar object seen in the solar system Now a team of alien-hunting scientists led by Russian billionaire Yuri Milner is scanning the object for radio signals Astronomers are set to scan an 'alien' comet for signs of extraterrestrial technology. The cigar-shaped asteroid, named 'Oumuamua by its discoverers, sailed past Earth last month and is the first interstellar object seen in the solar system. A team of alien-hunting scientists, led by Russian...

A unique opportunity to study the dwarf planet Haumea has led to an intriguing discovery: Haumea is surrounded by a ring. Add this to the already long list of unique things about the weird-shaped world with a dizzying rotation and a controversial discovery. On January 21, 2017 Haumea passed in front of a distant star, in an event known as an occultation. The background star can – pardon the pun – shine a light on the object passing in front, providing information about a distant object — such as size, shape, and density — that is otherwise difficult to obtain....

Kathryn Volk and Renu Malhotra at the University of Arizona have noticed some strange movement out in the Kuiper belt…movement that they believe could suggest the existence of a tenth planet. ... Objects in the Kuiper belt are far enough away from the other major bodies in our solar system that the gravitational influence of the large planets doesn’t impact them (at least, not to a measurable degree); however, their movements can still be predicted, thanks to sky surveys and a host of advanced technologies. The search for Planet Nine has lead scientists to believe that it is orbiting around...

With scalding surface temperatures of a hellish 4,327°C, researchers have discovered the hottest planet ever found. The planet, named KELT-9b, is 650 light years away, and so close to its host star its orbit takes just a day and a half. Researchers hope their findings will shed light on how planetary systems form around hot, massive stars.

Planetary Discovery around Ultracool Starby Paul Gilster on April 28, 2017 I have a special enthusiasm for microlensing as a means of exoplanet discovery. With microlensing, you never know what you’re going to come up with. Transits are easier to detect when the planet is close to its star, and hence transits more frequently. Radial velocity likewise sends its loudest signal when a planet is large and close. Microlensing, detecting the ‘bending’ of light from a background object as it is affected by a nearer star’s gravitational field, can turn up a planet whether near to its star or far,...

The International Astronomical Union currently defines a planet as: "a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit." A newly suggested definition takes a different approach:

In January, astronomers revealed evidence for the potential existence of another planet in the solar system. Researchers suggest that if this world — dubbed Planet Nine — exists, it could be about 10 times Earth's mass and orbit the sun at a distance about 500 times the distance from the Earth to the sun. Previous research suggested that Planet Nine would possess a highly tilted orbit compared with the relatively thin, flat zone in which the eight official planets circle the sun. This led scientists to investigate whether Planet Nine's slant might help explain other tilting seen elsewhere in the...

An artist's impression of the planet Proxima b, orbiting the red dwarf star Proxima Centauri, released by the European Southern Observatory on August 24, 2016 A rocky planet discovered in the "habitable" zone of the star nearest our Sun may be covered with oceans, researchers at France's CNRS research institute said Thursday. A team including CNRS astrophysicists have calculated the size and surface properties of the planet dubbed Proxima b, and concluded it may be an "ocean planet" similar to Earth. Scientists announced Proxima b's discovery in August, and said it may be the first exoplanet—planet outside our Solar System—to...

Astronomers hunting for Planet Nine have found some 50 new objects lying beyond the orbit of Neptune – including a few that may help them track down this elusive, distant world. The new discoveries, described in a paper accepted to the Astronomical Journal, mark another step toward finding this mysterious giant planet, which could help rewrite our understanding of our own solar system. In 2014, astronomers Scott Sheppard of the Carnegie Institution for Science and Chadwick Trujillo of Northern Arizona University announced that they’d found an object with the most distant orbit ever observed in the solar system – a...

In a paper that was recently accepted by The Astronomical Journal, Sheppard and Trujillo present their latest discoveries, which they claim are further constraining the location of Planet 9. ...Sheppard and Trujillo relied on information obtained by the Dark Energy Camera on the Victor Blanco 4-meter telescope in Chile and the Japanese Hyper Suprime-Camera on the 8-meter Subaru Telescope in Hawaii. ... Their most recent discovery was a small collection of more extreme objects who’s peculiar orbits differ from the extreme and inner Oort cloud objects, in terms of both their eccentricities and semi-major axes. As with discoveries made using...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2016 August 25 Closest Star has Potentially Habitable Planet Image Credit & License: Y. Beletsky (LCO), ESO, Pale Red Dot Team Explanation: The star closest to the Sun has a planet similar to the Earth. As announced yesterday, recent observations confirmed that this planet not only exists but inhabits a zone where its surface temperature could allow liquid water, a key ingredient for life on Earth. It is...

After scanning the vast reaches of the cosmos for Earth-like planets where life might exist, astronomers have found one right next door. NASA's New Horizons probe, the fastest spacecraft launched, left Earth hurtling toward Pluto at about 36,000 mph. At that speed, it would take more than 78,000 years to get there.