Free Republic

'); } //--> The peahen (at left) and the peacock (at right). The peacock's elaborate plumage and many other similar animal ornaments posed a troubling difficulty for Charles Darwin in his development of the theory of evolution, since they seemed to have no value for survival. The peacocks that were everywhere present in English gardens were a frustrating and ever-present reminder of the difficulty. "The sight of a feather in a peacock's tail", Darwin wrote, "whenever I gaze at it, makes me sick!". Darwin solved the problem with his theory of sexual selection, which posits that such ornaments evolved...

A smattering of water is buried deep inside the Moon and it arrived during the satellite's very early history, a new study concludes, when asteroids plunged into its churning magma oceans. How and when water got trapped in volcanic lunar rocks is a huge and open question for planetary scientists.

Explanation: To some, it looks like a giant chicken running across the sky. To others, it looks like a gaseous nebula where star formation takes place. Cataloged as IC 2944, the Running Chicken Nebula spans about 100 light years and lies about 6,000 light years away toward the constellation of the Centaur (Centaurus). The featured image, shown in scientifically assigned colors, was captured recently in an 11-hour exposure from a backyard near Melbourne, Australia. Two star clusters are visible: the Pearl Cluster seen on the far left, and Collinder 249 embedded in the nebula's glowing gas. Although difficult to discern...

Explanation: How did the universe evolve from such a smooth beginning? To help understand, computational cosmologists and NASA produced the featured time-lapse animated video depicting a computer simulation of part of the universe. The 100-million light-year simulation starts about 20 million years after the Big Bang and runs until the present. After a smooth beginning, gravity causes clumps of matter to form into galaxies which immediately begin falling toward each other. Soon, many of them condense into long filaments while others violently merge into a huge and hot cluster of galaxies. Investigating of potential universe attributes in simulations like this...

Explanation: Mars will look good in Earth's skies over the next few days -- but not this good. To get a view this amazing, a spacecraft had to actually visit the red planet. Running across the image center, though, is one the largest canyons in the Solar System. Named Valles Marineris, the grand valley extends over 3,000 kilometers long, spans as much as 600 kilometers across, and delves as much as 8 kilometers deep. By comparison, the Earth's Grand Canyon in Arizona, USA is 800 kilometers long, 30 kilometers across, and 1.8 kilometers deep. The origin of the Valles Marineris...

An international team of scientists, including the University of Kentucky's Renbin Yan, have uncovered a new class of galaxies, called "red geysers," with supermassive black hole winds so hot and energetic that stars can't form. Over the last few billion years, a mysterious kind of "galactic warming" has caused many galaxies to change from a lively place where new stars formed every now and then to a quiet place devoid of fresh young stars. But the mechanism that produces this dramatic transformation and keeps galaxies quiet has been one of the biggest unsolved mysteries in galaxy evolution. "These galaxies have...

All the planets in our solar system orbit close to the sun's equatorial plane. Of the eight confirmed planets, the Earth's orbit is the most tilted, but even that tilt is still small, at just seven degrees. It was natural, then, for astronomers to expect that planets orbiting other stars would behave the same way... But in recent years, new observations have revealed that the story is somewhat more complicated, at least for the oddest planets known, the Hot Jupiters. ... Comparable in mass to Jupiter, they move on incredibly short period orbits, almost skimming the surfaces of their host...

An artist's conception of Kepler-62f, a planet in the 'habitable zone' of a star located about 1,200 light-years from Earth. Credit: NASA Ames/JPL-Caltech/T. Pyle ========================================================================================================================= A distant planet known as Kepler-62f could be habitable, a team of astronomers reports. The planet, which is about 1,200 light-years from Earth in the direction of the constellation Lyra, is approximately 40 percent larger than Earth. At that size, Kepler-62f is within the range of planets that are likely to be rocky and possibly could have oceans, said Aomawa Shields, the study's lead author and a National Science Foundation astronomy and astrophysics postdoctoral fellow...

Explanation: The Cat's Eye Nebula (NGC 6543) is one of the best known planetary nebulae in the sky. Its more familiar outlines are seen in the brighter central region of the nebula in this impressive wide-angle view. But the composite image combines many short and long exposures to also reveal an extremely faint outer halo. At an estimated distance of 3,000 light-years, the faint outer halo is over 5 light-years across. Planetary nebulae have long been appreciated as a final phase in the life of a sun-like star. More recently, some planetary nebulae are found to have halos like this...

Explanation: A jewel of the southern sky, the Great Carina Nebula, also known as NGC 3372, spans over 300 light-years, one of our galaxy's largest star forming regions. Like the smaller, more northerly Great Orion Nebula, the Carina Nebula is easily visible to the unaided eye, though at a distance of 7,500 light-years it is some 5 times farther away. This gorgeous telescopic close-up reveals remarkable details of the region's central glowing filaments of interstellar gas and obscuring cosmic dust clouds. The field of view is over 50 light-years across. The Carina Nebula is home to young, extremely massive stars,...

If Martians exist, they'll be closer to Earth on Memorial Day than they have been in 11 years. This Monday, around 5:34 p.m. EDT, when many Americans may be enjoying a holiday barbecue, the Red Planet will be the closest it has been to Earth in more than a decade, coming within 46.8 million miles, according to NASA. The relatively close encounter with Earth comes a week after the Martian opposition, when Mars and the sun lined up on exact opposite sides of the Earth.

Had you searched the sky with a telescope just a few hundred thousand years ago, you would have struggled to find a red planet. Instead, you would have seen a gleaming-white ice ball where Mars should be. A team of astronomers led by Isaac Smith, an astrophysicist at the Southwest Research Institute in Boulder, Colorado, has collected the first concrete evidence that Mars has just exited an extreme ice age, one so intense it would have put Earth's recent frosty foray to shame. Using cameras and a radar-pinging device on board NASA's Mars Reconnaissance Orbiter, Smith's team deduced this history...

Astronomers used the Harlan J. Smith Telescope at the University of Texas at Austin's McDonald Observatory near Fort Davis, Texas, to search for a planet around star CI Tau. Credit: Ethan Tweedie Photography ================================================================================================== In contradiction to the long-standing idea that larger planets take longer to form, U.S. astronomers today announced the discovery of a giant planet in close orbit around a star so young that it still retains a disk of circumstellar gas and dust. "For decades, conventional wisdom held that large Jupiter-mass planets take a minimum of 10 million years to form," said Christopher Johns-Krull, the lead author...

Explanation: The prominent ridge of emission featured in this sharp, colorful skyscape is cataloged as IC 5067. Part of a larger emission nebula with a distinctive shape, popularly called The Pelican Nebula, the ridge spans about 10 light-years following the curve of the cosmic pelican's head and neck. This false-color view also translates the pervasive glow of narrow emission lines from atoms in the nebula to a color palette made popular in Hubble Space Telescope images of star forming regions. Fantastic, dark shapes inhabiting the 1/2 degree wide field are clouds of cool gas and dust sculpted by the winds...

Explanation: This sharp telescopic field of view holds two bright galaxies. Barred spiral NGC 5101 (top right) and nearly edge-on system NGC 5078 are separated on the sky by about 0.5 degrees or about the apparent width of a full moon. Found within the boundaries of the serpentine constellation Hydra, both are estimated to be around 90 million light-years away and similar in size to our own large Milky Way galaxy. In fact, if they both lie at the same distance their projected separation would be only 800,000 light-years or so. That's easily less than half the distance between the...

Strange plumes in Mars’ atmosphere first recorded by amateur astronomers four year ago have planetary scientists still scratching their heads. But new data from European Space Agency’s orbiting Mars Express points to coronal mass ejections from the Sun as the culprit. On two occasions in 2012 amateurs photographed cloud-like features rising to altitudes of over 155 miles (250 km) above the same region of Mars. By comparison, similar features seen in the past haven’t exceeded 62 miles (100 km). On March 20th of that year, the cloud developed in less than 10 hours, covered an area of up to 620...

Explanation: That's not lightning, and it did not strike between those mountains. The diagonal band is actually the central band of our Milky Way Galaxy, while the twin peaks are actually called the Spanish Peaks -- but located in Colorado, USA. Although each Spanish peak is composed of a slightly different type of rock, both are approximately 25 million years old. This serene yet spirited image composite was meticulously created by merging a series of images all taken from the same location on one night and early last month. In the first series of exposures, the background sky was built...

Scientists have been searching for the origin of some of the most precious metals on Earth - including gold, silver, and platinum - for almost six decades. And now we might finally have the answer. Heavy, and often valuable elements like these are called r-process elements, and they require an incredible amount of energy to produce. So far, no one's been able to explain how they came to exist in the Universe. But the discovery that an ancient dwarf galaxy called Reticulum II - about 98,000 light-years from Earth - has stars that contain a "whopping" amount of these metals...

Explanation: Why is there more matter than antimatter in the Universe? To better understand this facet of basic physics, energy departments in China and the USA led in the creation of the Daya Bay Reactor Neutrino Experiment. Located under thick rock about 50 kilometers northeast of Hong Kong, China, eight Daya Bay detectors monitor antineutrinos emitted by six nearby nuclear reactors. Featured here, a camera looks along one of the Daya Bay detectors, imaging photon sensors that pick up faint light emitted by antineutrinos interacting with fluids in the detector. Early results indicate an unexpectedly high rate of one type...

Explanation: What created this great arc in space? This arcing, graceful structure is actually a bow shock about half a light-year across, created as the wind from young star LL Orionis collides with the Orion Nebula flow. Adrift in Orion's stellar nursery and still in its formative years, variable star LL Orionis produces a wind more energetic than the wind from our own middle-aged sun. As the fast stellar wind runs into slow moving gas a shock front is formed, analogous to the bow wave of a boat moving through water or a plane traveling at supersonic speed. The slower...