Astronomy
Ocean on Enceladus
Will Ocean Discovery On Enceladus Spur Life-Hunting Missions to Icy Moons of Saturn, Jupiter?
Astronomers are hoping that the discovery of a subsurface ocean on Saturn's icy moon Enceladus will build momentum for life-hunting missions to the outer solar system.
http://www.space.com/25348-enceladus-ocean-europa-life-hunting-missions.html?cmpid=557141
Researchers announced their discovery of the deep watery ocean on Enceladus on Thursday (April 3) in the journal Science, confirming suspicions held by many scientists since 2005, when NASA's Cassini spacecraft spied geysers of ice and water vapor erupting from Enceladus' south pole.
The discovery vaults Enceladus into the top tier of life-hosting candidates along with Europa, an ice-sheathed moon of Jupiter that also hosts a subterranean ocean. Both frigid satellites bear much closer investigation, researchers say. [6 Most Likely Places for Alien Life in the Solar System]
Dwarf Planet found
New Dwarf Planet Found at Solar System's Edge, Hints at Possible Faraway 'Planet X'
By Mike Wall, Senior Writer | March 26, 2014 02:00pm ET
http://www.space.com/25218-dwarf-planet-discovery-solar-system-edge.html?cmpid=556790
Astronomers have found a new dwarf planet far beyond Pluto's orbit, suggesting that this distant realm contains millions of undiscovered objects — including, perhaps, a world larger than Earth.
The newfound celestial body, called 2012 VP113, joins the dwarf planet Sedna as a confirmed resident of a far-flung and largely unexplored region scientists call the "inner Oort Cloud." Further, 2012 VP113 and Sedna may have been pulled into their long, looping orbits by a big planet lurking unseen in these frigid depths.
"These two objects are just the tip of the iceberg," study co-author Chadwick Trujillo, of the Gemini Observatory in Hawaii, told Space.com. "They exist in a part of the solar system that we used to think was pretty devoid of matter. It just goes to show how little we actually know about the solar system." [New Dwarf Planet Photos: Images of 2012 VP113]
Mars Meteorite
Mars Meteorite with Odd 'Tunnels' & 'Spheres' Revives Debate Over Ancient Martian Life
By Megan Gannon, News Editor | February 28, 2014 01:00am ET
http://www.space.com/24834-strange-mars-meteorite-life-evidence-debate.html?cmpid=556718
The discovery of tiny carbon-rich balls and tunnels inside a Martian meteorite has once again raised the possibility that the Red Planet was teeming with primitive life millions of years ago.
The meteorite, which fell to Earth during the Stone Age, contains microscopic burrows and spheres that resemble the marks microorganisms leave when they eat through rocks on Earth, scientists report in the journal Astrobiology this month. What's more, these features seem to have been pressed into the Mars rock before it was hurled off the Red Planet by an impact event, the researchers add.
The authors of the new research are not claiming they've found evidence of ancient life on Mars. In fact, nowhere in their paper do they use the word "life." (Their preferred term is "biotic activity.") But their findings revive the debate about the possibility of microbes in Mars' past and highlight how much information scientists can actually glean from Martian meteorites that end up on Earth. [The Search for Life on Mars (A Photo Timeline)]
Exoplanets
Population of Known Alien Planets Nearly Doubles as NASA Discovers 715 New Worlds
By Mike Wall, Senior Writer | February 26, 2014 01:01pm ET
http://www.space.com/24824-alien-planets-population-doubles-nasa-kepler.html?cmpid=556717
View full size imageNASA's Kepler space telescope has discovered more than 700 new exoplanets, nearly doubling the current number of confirmed alien worlds.
The 715 newfound planets, which scientists announced today (Feb. 26), boost the total alien-world tally to between 1,500 and 1,800, depending on which of the five main extrasolar planet discovery catalogs is used. The Kepler mission is responsible for more than half of these finds, hauling in 961 exoplanets to date, with thousands more candidates awaiting confirmation by follow-up investigations.
"This is the largest windfall of planets — not exoplanet candidates, mind you, but actually validated exoplanets — that's ever been announced at one time," Douglas Hudgins, exoplanet exploration program scientist at NASA's Astrophysics Division in Washington, told reporters today. [Kepler's Exoplanet Bonanza Explained (Infographic)]
Coldest Place On Earth
From: noreply@nasascience.org
To: snglist@nasascience2.org
Subject: The Coldest Place on Earth
Date: Tue, 10 Dec 2013 03:09:56 -0500
NASA Science News for Dec. 10, 2013 Earth-orbiting satellites have found the coldest place on Earth. It's a group of hollows in Antarctica where temperatures can dip below minus 133.6 degrees Fahrenheit (minus 92 degrees Celsius) on a clear winter night.
FULL STORY: http://science.nasa.gov/science-news/science-at-nasa/2013/09dec_coldspot/
Four Blood Moons: Total Lunar Eclipse Series Not a Sign of Apocalypse
Geoff Gaherty Starry Night Education | April 09, 2014 12:30pm ET
http://www.space.com/25409-four-blood-moons-tetrad-lunar-eclipse.html?cmpid=557146
There has been a lot of interest recently in an upcoming series of lunar eclipses that begins April 15. These are usually described as "four blood moons" and taken by some to prophesy upcoming disasters.
The total lunar eclipse of April 15 will begin a so-called tetrad series of eclipses that is making the rounds online as a potential harbinger of doom, due in part to a recent book on the four blood moons that makes the dubious claim.
Astronomers rarely if ever use the term blood moon. When they do, they are usually using it as an alternate name for the Hunter's Moon, the full moon that follows the Harvest Moon, usually in late October. The Hunter's Moon, like the Harvest Moon, rises slowly on autumn evenings so that it shines through a thick layer of the Earth's atmosphere, and is colored red by Rayleigh scattering and air pollution. [Four Blood Moons: Lunar Eclipse Tetrad Explained (Video)]
This NASA graphic depicts the position of the moon in Earth's shadow during the total lunar eclipse of April 15, 2014 at 3 a.m. ET. It is the first of four consecutive total lunar eclipses, a tetrad, between April 2015 and September 2015.
Credit: NASA
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Lunar eclipses explained
A lunar eclipse is something quite different. It occurs when the moon passes through the Earth's shadow.
The Earth's shadow consists of two parts: a dark inner core called the "umbra," and a lighter outer part called the "penumbra." Rather than being truly dark, the inner shadow is usually tinted orange or red by light passing through the ring of atmosphere surrounding the Earth.
Depending on the atmospheric conditions on Earth in the band of atmosphere through which the sun's light is passing, the umbra may take on a range of colors from light coppery-red to almost total black. The light illuminating an eclipsed moon is coming from thousands of sunsets and sunrises around the Earth. During some eclipses, these sunsets and sunrises are clear, and much light passes through; during others, clouds may block the light, causing a dark eclipse.
The blood moon
On rare occasions, the light reaching the moon is exactly the color of blood, but there is no way of predicting this in advance. So there are no grounds to call any particular lunar eclipse a blood moon until it actually shows its color.
This NASA graphic shows where the total lunar eclipse of April 14-15, 2014 will be visible from. The lunar eclipse coincides with April's full moon and is the first of four total lunar eclipes (a tetrad) between April 2014 and September 2015.
Credit: NASA/JPL-Caltech
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Because the moon's orbit is slightly tilted with respect to the sun's path across the sky, most of the time the moon passes above or below the Earth's shadow, and no eclipse occurs. Sometimes it passes only through the penumbra and produces what is called a penumbral eclipse, a moon so lightly shaded that the casual observer might not even notice a difference. There were two such penumbral eclipses in 2013, on May 25 and Oct. 18.
Sometimes the moon only dips slightly into the central shadow, and it produces a partial lunar eclipse. One of these occurred last year, on April 25.
The rarest of all lunar eclipses are those in which the moon passes through the darkest part of the shadow, a true total lunar eclipse. This last happened on Dec. 10, 2011.
The total lunar eclipse of October 8 2014.
Credit: Starry Night software
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Four Blood Moons: The lunar eclipse tetrad
What is unusual about this month's lunar eclipse is that it is the first of a series of four total lunar eclipses in a row. Called a tetrad, such a series of four total eclipses in a row is a fairly rare event. The last such series happened in the years 2003 and 2004. It will only occur seven more times in the current century.
So while a tetrad of total lunar eclipses is somewhat rare, it is not extraordinarily so, and probably nothing to make a fuss about. After all, the only thing that happens during a lunar eclipse is that the moon spends a couple of hours passing through the Earth's shadow, hardly something to be concerned about.
Unfortunately, there are still many superstitious people in the world. Such is the case in the book "Four Blood Moons: Something Is About to Change" (Worthy Publishing, 2013) by John Hagee, which suggests a link between the new total lunar eclipse tetrad and biblical prophecy about the end times When the mechanisms behind eclipses were less well understood, they were thought to be omens of bad tidings, just as comets were. Now people know that these are just normal events in the clockwork of the solar system, things which have occurred regularly for thousands of years and which will occur for thousands of years into the future.
Associations between "disastrous" events and normal astronomical events are all fabrications of the human mind, as people attempt to find explanations for why disasters affect them. Because of the Internet and cable news channels, people now hear reports of disasters from around the world, including earthquakes, tsunamis and
volcanic eruptions, which they never would have been aware of in the past. It's almost inevitable that something bad will happen right after an eclipse or a visit from a comet.
As an ardent skywatcher who derives much pleasure from beautiful events like lunar eclipses, it saddens me that there are "prophets of doom" in the world who view these life-enriching events as portents of disaster.
The good news about these forthcoming lunar eclipses is that all four will be visible to most skywatchers in North America. I hope that you will manage to observe one or more of them, and share their beauty with your friends. The eclipse on April 15 will require most North Americans to stay up into the wee hours of the morning, but it will be well worth it.
Editor's Note: If you snap an amazing picture of the April 15 total lunar eclipse or any other night sky view that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at spacephotos@space.com.
This article was provided to Space.com by Simulation Curriculum, the leader in space science curriculum solutions and the makers of Starry Night and SkySafari. Follow Starry Night on Twitter @StarryNightEdu. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com.
EDITOR'S RECOMMENDATIONS A Tetrad Of Lunar Eclipses Starts In April | Video Photos: Total Lunar Eclipse of December 2011 Close Mars, Lunar Eclipse And Lyrid Meteors - April 2014 Skywatching Video The Moon: 10 Surprising Lunar Facts
Mars Water
New Evidence for a Mars Water Reservoir
http://science.nasa.gov/science-news/science-at-nasa/2014/19dec_marswater/
Dec. 19, 2014: NASA and an international team of planetary scientists have found evidence in meteorites on Earth that indicates Mars has a distinct and global reservoir of water or ice near its surface.
Though controversy still surrounds the origin, abundance and history of water on Mars, this discovery helps resolve the question of where the “missing Martian water” may have gone. Scientists continue to study the planet’s historical record, trying to understand the apparent shift from an early wet and warm climate to today’s dry and cool surface conditions.
The reservoir’s existence also may be a key to understanding climate history and the potential for life on Mars. The team’s findings are reported in the journal Earth and Planetary Science Letters.
“There have been hints of a third planetary water reservoir in previous studies of Martian meteorites, but our new data require the existence of a water or ice reservoir that also appears to have exchanged with a diverse set of Martian samples,” said Tomohiro Usui of Tokyo Institute of Technology in Japan, lead author of the paper and a former NASA/Lunar and Planetary Institute postdoctoral fellow. “Until this study there was no direct evidence for this surface reservoir or interaction of it with rocks that have landed on Earth from the surface of Mars.”
Researchers from the Tokyo Institute of Technology, the Lunar and Planetary Institute in Houston, the Carnegie Institution for Science in Washington and NASA’s Astromaterials Research and Exploration Science Division, located at the agency’s Johnson Space Center in Houston, studied three Martian meteorites.
The samples revealed water comprised of hydrogen atoms that have a ratio of isotopes distinct from that found in water in the Red Planet’s mantle and current atmosphere. Isotopes are atoms of the same element with differing numbers of neutrons.
While recent orbiter missions have confirmed the presence of subsurface ice, and melting ground-ice is believed to have formed some geomorphologic features on Mars, this study used meteorites of different ages to show that significant ground water-ice may have existed relatively intact over time.
Researchers emphasize that the distinct hydrogen isotopic signature of the water reservoir must be of sufficient size that it has not reached isotopic equilibrium with the atmosphere.
“The hydrogen isotopic composition of the current atmosphere could be fixed by a quasi-steady-state process that involves rapid loss of hydrogen to space and the sublimation from a widespread ice layer,” said coauthor John Jones, a JSC experimental petrologist and member of NASA’s Mars Curiosity rover team.
Curiosity’s observations in a lakebed, in an area called Mount Sharp, indicate Mars lost its water in a gradual process over a significant period of time.
“In the absence of returned samples from Mars, this study emphasizes the importance of finding more Martian meteorites and continuing to study the ones we have with the ever-improving analytical techniques at our disposal,” said co-author Conel Alexander, a cosmochemist at the Carnegie Institution for Science.
In this investigation, scientists compared water, other volatile element concentrations and hydrogen isotopic compositions of glasses within the meteorites, which may have formed as the rocks erupted to the surface of Mars in ancient volcanic activity or by impact events that hit the Martian surface, knocking them off the planet.
“We examined two possibilities, that the signature for the newly identified hydrogen reservoir either reflects near surface ice interbedded with sediment or that it reflects hydrated rock near the top of the Martian crust,” said coauthor and JSC cosmochemist Justin Simon. “Both are possible, but the fact that the measurements with higher water concentrations appear uncorrelated with the concentrations of some of the other measured volatile elements, in particular chlorine, suggests the hydrogen reservoir likely existed as ice.”
The information being gathered about Mars from studies on Earth, and data being returned from a fleet of robotic spacecraft and rovers on and around the Red Planet, are paving the way for future human missions on a journey to Mars in the 2030s.
These findings can be viewed online in their entirety at: http://go.nasa.gov/1zwSjTa
Credits and more information:
Production editor: Dr. Tony Phillips | Credit: Science@NASA
For more about the ARES Division at JSC, visit: http://ares.jsc.nasa.gov
Learn about NASA’s Journey to Mars at: http://www.nasa.gov/content/nasas-journey-to-mars/
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Saturn's rings
Surprising Math Rules of Saturn's Rings Revealed
by Sarah Lewin, Staff Writer | August 10, 2015 06:57am ET
As particles race around Saturn at breakneck speeds, their jostling and crashing may look random and haphazard — but a new mathematical theory brings a simple kind of order to the chaos that will help reveal more about rings across the universe.
A group of physicists, mathematicians and astronomers has more rigorously explained a longstanding mystery of Saturn's rings: why the distribution of different particle sizes, ranging from inches to more than 30 feet (10 meters) across, follows a very simple ratio. Their model also suggests why very large bodies in the rings never last long.
The theory not only explains the regularity of Saturn's rings, but also may reveal more about planets' and asteroids' ages and conditions based on the distribution of their rings. [Photos: Saturn's Glorious Rings Up Close]
"The law follows from a 1-centimeter-sized (0.4 inches) particle to house-sized," said Nikolai Brilliantov, a mathematician at the University of Leicester in England and lead author of the new study. "This is mathematically quite beautiful, but [we had] no idea why it happens. Now, we understand that it's perfectly correct, and we know why, and can prove that there is a very universal mechanism behind these particular features."
Saturn is surrounded by immense rings built of chunks of water ice, with a sprinkling of rocky material. The rings can reach a width of 185,000 miles (300,000 kilometers), and the particles can travel at thousands of miles per hour. Researchers have found that the rings' particles are loose and porous. When two particles collide, if they're moving slowly enough, they will merge into one — but if they're moving too quickly, they'll shatter. The new model shows mathematically how this simple behavior agrees with the strangely precise distribution of the particle's sizes. [Saturn Quiz: Do You Know the Ringed Planet?]
Since the 1980s, researchers have noticed a strict ratio in the sizes of particles in Saturn's rings — that it roughly followed an "inverse cube law." For instance, a particle two times larger than another will be eight times less common, and a particle three times larger will be 27 times less common. The new mathematical model starts with merging and fracturing particles, and finds that the distribution would be very similar to this rule of 3 — between 2.75 and 3.5. And it would have that same drop-off with very few particles above a certain size.
"Usually, astrophysicists try to solve their problems, but they are not equipped with the new [mathematical] tools," Brilliantov said. Over the course of seven years, the researchers studied the mechanical properties of ice, collisions and fragmentation to work into their model of how granules behave, verifying that the ratio can emerge out of real-world starting rules through calculations on a Moscow supercomputer.
And the rule is even broader than they thought when starting out: Only two years ago, researchers found that asteroids have rings, too. And the ringed asteroids Chariklo and Chiron fit Saturn's mold, said Paul Krapivsky, a statistical physicist at Boston University and a co-author of the study. The asteroids with measured rings are much, much smaller than Saturn, Krapivsky told Space.com. But yet "they still have similar rings," he said. "And not just similar rings — they have similar distributions. It's quite universal."
How well the rule applies to edge cases, where the rings are very different from Saturn's, remains to be seen.
"It's an interesting theoretical work," said Shawn Brooks, a planetary scientist who works on NASA's Cassini mission to Saturn and researches Saturn's rings but was not involved with this study.
"They're bringing in lots of physics in empirical ways to build this model that describes how ring particles both clump up and aggregate, and also collide and break each other apart, and looks to understand what the balance between the two of them is," he told Space.com. "The model gives a result that is consistent with what observers have seen." [Latest Saturn Photos by Cassini]
However, Brooks said the model's physics might not apply to systems with an excessive number of collisions or very few collisions, and thus further observational research would be needed to see when those systems would hold to the model.
As it is verified in more cases, the model can teach researchers about planets and the asteroids that the rings surround. "Now we know how the rings must be constructed," Brilliantov told Space.com. "Suppose we discover new rings, of some planet — just [by] measuring the distribution of particle size of the ring, we can say whether these rings are young or whether they've experienced some catastrophic impact in the reasonable past. If they're in the form of inverse cube … nothing happened for the last 10,000 years."
Also, by looking at the maximum particle size, researchers will be able to learn more about the substances from which the rings formed.
"It is important to study the ring particle-size distribution and how it varies with location," Jeff Cuzzi, the rings-and-dust interdisciplinary scientist for the Cassini mission who was also not involved in the study, wrote in an email. "This can tell us about the vigor of the local ring dynamics."
Cuzzi said this work confirms previous research on how Saturn's rings form, and describes it in a more general mathematical sense. "The general conclusion of all work to date is that the particles are loose aggregates, not solid icebergs, and that the size distributions we see today are not primordial but are highly evolved and re-evolved by local dynamics," he said.
As the tricky process of measuring far-off rings is repeated for more planets and asteroids, the research team will have more and more situations to feed into the model. Saturn's rings have reached a balanced, steady state, but other rings in the universe may not be so well-established: Brilliantov says the next step would be to delve into how rings evolve over time to settle into a balance.
"In our solar system, there are plenty of rings which are not explored," Brilliantov said. "We know that Neptune has planetary rings; asteroids have rings. We know that they do exist, but nothing is known about the distribution of particle size … If we have enough information, we can apply a more complicated, more beautiful, more comprehensive theory for these systems. There are a lot of things to do."
Email Sarah Lewin at slewin@space.com or follow her @SarahExplains. Follow us @Spacedotcom, Facebook and Google+. Original article on Space.com
http://www.space.com/30197-saturn-rings-math-rule.html?cmpid=NL_SP_weekly_2015-08-10
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