Posted on by Jerry Coffey

How Did Neptune Get Its Name?

Neptune Hurricanes
The "surface" of Neptune, its uppermost layer, is one of the most turbulent and active places in the Solar System. Credit: NASA/JPL

How did Neptune get its name? Shortly after its discovery, Neptune was only referred to as “the planet exterior to Uranus” or as “Le Verrier’s planet”. The first suggestion for a name came from Johann Galle, who proposed the name Janus. Another proposal was Oceanus. Urbain Le Verrier, who discovered the planet, claimed the right to name his discovery: Neptune. Soon Neptune became the internationally accepted name.

In roman mythology, Neptune was the god of the sea. The demand for a mythological name seemed to be in keeping with the nomenclature of the other planets, all of which, except for Earth, were named for Greek and Roman mythology. Most languages today use some variant of the name “Neptune” for the planet.

Now that you know how the planet was named, how about some facts about the planet itself. Size wise, the planet has an equatorial radius 24,764 km, a polar radius of 24,341 km, and a surface area of 7.6408×10,sup>9km2. It has a volume of 6.254×1013km3, a mass of 1.0243×1026kg, and a mean density of 1.638 g/cm3.

Its atmosphere is composed primarily of hydrogen and helium along with traces of hydrocarbons and nitrogen. It also contains a high proportion of ices like: water, ammonia, and methane. Astronomers occasionally categorize Neptune as an ice giant. The interior of Neptune is primarily composed of ices and rock. Traces of methane in the outermost regions account for the planet’s blue appearance. Neptune’s atmosphere is notable for its active and visible weather patterns. These weather patterns are driven by the strongest sustained winds of any planet in the Solar System, with recorded wind speeds as high as 2,100 km/h.Because of its great distance from the Sun, Neptune’s outer atmosphere is one of the coldest places in the Solar System, with temperatures at its cloud tops approaching ?218°C. Temperatures at the planet’s center are approximately 5,000°C. Neptune is one of the most interesting planets in our solar system. There are plenty of other articles about the planet here on Universe Today.

We have written many articles about Neptune for Universe Today. Here’s an article about the size of Neptune, and here’s an article about the atmosphere of Neptune.

If you’d like more information on Neptune, take a look at Hubblesite’s News Releases about Neptune, and here’s a link to NASA’s Solar System Exploration Guide to Neptune.

We’ve also recorded an entire episode of Astronomy Cast all about Neptune. Listen here, Episode 63: Neptune.

Source: NASA

Posted on by Jason Major

Saturn’s “Wispy” Moon Has An Oxygen Atmosphere

Cassini has detected molecular oxygen ions around Saturn's icy Dione

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There’s oxygen around Dione, a research team led by scientists at New Mexico’s Los Alamos National Laboratory announced on Friday. The presence of molecular oxygen around Dione creates an intriguing possibility for organic compounds — the building blocks of life — to exist on other outer planet moons.

Dione's signature "wispy lines" are actually the bright walls of long cliff faces. (NASA/JPL/SSI)

One of Saturn’s 62 known moons, Dione (pronounced DEE-oh-nee) is 698 miles (1,123 km) in diameter. It orbits Saturn at about the same distance that our Moon orbits Earth. Heavily cratered and crisscrossed by long, bright scarps, Dione is made mostly of water ice and  rock. It makes a complete orbit of Saturn every 2.7 days.

Data acquired during a flyby of the moon by the Cassini spacecraft in 2010 have been found by the Los Alamos researchers to confirm the presence of molecular oxygen high in Dione’s extremely thin atmosphere — so thin, in fact, that scientists prefer the term exosphere.

While you couldn’t take a deep breath on Dione, the presence of O2 indicates a dynamic process in action.

“The concentration of oxygen in Dione’s atmosphere is roughly similar to what you would find in Earth’s atmosphere at an altitude of about 300 miles,” said Robert Tokar, researcher at Los Alamos National Laboratory and lead author of the paper published in Geophysical Research Letters.  “It’s not enough to sustain life, but—together with similar observations of other moons around Saturn and Jupiter—these are definitive examples of a process by which a lot of oxygen can be produced in icy celestial bodies that are bombarded by charged particles or photons from the Sun or whatever light source happens to be nearby.”

On Dione the energy source is Saturn’s powerful magnetic field. As the moon orbits the giant planet, charged ions in Saturn’s magnetosphere slam into the surface of Dione, stripping oxygen from the ice on its surface and crust. This molecular oxygen (O2) flows into Dione’s exosphere, where it is then steadily blown into space by — once again — Saturn’s magnetic field.

Cassini’s instruments detected the oxygen in Dione’s wake during an April 2010 flyby.

Molecular oxygen, if present on other moons as well (say, Europa or Enceladus) could potentially bond with carbon in subsurface water to form the building blocks of life. Since there’s lots of water ice on moons in the outer solar system, as well as some very powerful magnetic fields emanating from planets like Jupiter and Saturn, there’s no reason to think there isn’t more oxygen to be found… in our solar system or elsewhere.

Read the news release from the Los Alamos National Laboratory here.

 

Image credits: NASA/JPL/Space Science Institute. Research citation: Tokar, R. L., R. E. Johnson, M. F. Thomsen, E. C. Sittler, A. J. Coates, R. J. Wilson, F. J. Crary, D. T. Young, and G. H. Jones (2012), Detection of exospheric O2+ at Saturn’s moon Dione, Geophys. Res. Lett., 39, L03105, doi:10.1029/2011GL050452.

 

Posted on by Jason Major

Today’s Martian Weather: Partly Cloudy

Clouds obscure the surface of Mars (NASA/JPL/ASU)

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Changing seasons in Mars’ northern hemisphere brings a change in the weather, and the clouds have rolled in to cover part of the polar surface in this intriguing image from the Mars Odyssey spacecraft.

Mars Odyssey’s THEMIS visual imager (VIS) captured this image on Jan. 24, 2012, as it passed over the Red Planet’s northern pole during one of its 2-hour-long orbits.

Clouds on Mars have been seen before, both from orbit and from the surface. They are made up of fine water ice particles and are usually at altitudes of 10 to 15 km high. Read more about Martian weather here.

The full THEMIS scan of the area is below.

Martian polar clouds as seen by THEMIS

The area imaged is about 21 km wide by 73 km high  (13 x 45 miles).

Image credit: NASA / JPL / Arizona State University. Hat-tip to Mr. Bill Dunford at Riding With Robots (@ridingrobots). 

Posted on by Jason Major

Mercury Down Under

MESSENGER wide-angle camera image of Mercury's southern hemisphere.

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NASA’s MESSENGER spacecraft, about to wrap up its first full year in orbit around Mercury, captured this view of the planet’s heavily-cratered southern hemisphere on August 28, 2011. Because of its orbit, MESSENGER gets particularly good panoramic views of Mercury’s underside.

Here’s why…

MESSENGER’s orbit, established on March 18, 2011 at 00:45 UTC, is not a simple circling path around the first rock from the Sun. Instead it is highly elliptical, bringing it 124 miles (200 km) above Mercury’s north pole at its closest and more than 9,420 miles (15,193 km) from its south pole at its farthest! (See diagram below.)

The close approaches over the northern hemisphere allow MESSENGER to study the Caloris basin, Mercury’s largest surface feature and, at over 960 miles (1,550 km) across, one of the largest impact craters in the entire Solar System.

The view of Mercury’s southern hemisphere above features some notable craters as well: the relatively youthful 444-mile (715-km) -wide Rembrandt basin is seen at top right, while the smaller pit-floor crater Kipling can be discerned to its left, just below the planet’s limb.

When craters are larger than 300 km in diameter, they are referred to as basins.

During its 12 months in orbit MESSENGER will have experienced only two days on Mercury! This is because Mercury rotates very slowly on its axis, completing a full solar day (sunrise to sunrise) every 176 Earth days. (And you thought your work day seemed to last forever!)

Three perspectives of MESSENGER's orbit.

Find out more about the MESSENGER mission here.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. 

Posted on by Jason Major

Degas: a Crater Painted Blue

MESSENGER wide-angle camera image of Degas crater

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This image, acquired by NASA’s MESSENGER spacecraft on December 12, 2011, reveals the blue coloration of the 32-mile (52-km) -wide Degas crater located in Mercury’s Sobkou Planitia region.

Degas’ bright central peaks are highly reflective in this view, and may be surrounded by hollows — patches of sunken, eroded ground first identified by MESSENGER last year.

Such blue-colored material within craters has been increasingly identified as more of Mercury’s surface is revealed in detail by MESSENGER images. It is likely due to an as-yet-unspecified type of dark subsurface rock, revealed by impact events.

The slightly larger, more eroded crater that Degas abuts is named Brontë.

The image was acquired with MESSENGER’s Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS), using filters 9, 7, 6 (996, 748, 433 nanometers) in red, green, and blue, respectively.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

Posted on by Jason Major

Kuiper’s Color Close-Up

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The pale-orange coloration around the 39-mile (62-km) -wide Kuiper crater on Mercury is evident in this image, a color composition made from targeted images acquired by NASA’s MESSENGER spacecraft on September 2, 2011.

The color may be due to compositional differences in the material that was ejected during the impact that formed the crater.

Kuiper crater is named after Gerard Kuiper, a Dutch-American astronomer who was a member of the Mariner 10 team. He is regarded by many as the father of modern planetary science.

“Kuiper studied the planets… at a time when they were scarcely of interest to other astronomers. But with new telescopes and instrumentation, he showed that there were great things to discover, which is as true today as it was then.”

– Dr. Bill McKinnon, Professor of Planetary Sciences at Washington University in St. Louis

Airless worlds like Mercury are constantly bombarded with micrometeoroids and charged solar particles in an effect known as “space weathering”. Craters with bright rays — like Kuiper — are thought to be relatively young because they have had less exposure to space weathering than craters without such rays.

See the original image release on the MESSENGER site here.

Image credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

Posted on by Jason Major

Russia To Try Again For Phobos-Grunt?

Poster art for the Russian Phobos-Grunt mission. Russian Federal Space Agency)/IKI

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Russia says “eish odin ras”* for its Mars moon lander mission, according to Roscomos chief Vladimir Popovkin.

If the European Space Agency does not include Russia in its ExoMars program, a two-mission plan to explore Mars via orbiter and lander and then with twin rovers (slated to launch in 2016 and 2018, respectively), Roscosmos will try for a “take-two” on their failed Phobos-Grunt mission.

“We are holding consultations with the ESA about Russia’s participation in the ExoMars project… if no deal is reached, we will repeat the attempt,” said Popovkin on Tuesday.

Phobos-Grunt, an ambitious mission to land on the larger of Mars’ two moons, collect samples and return them to Earth, launched successfully on November 9, 2011. It became caught in low-Earth orbit shortly afterwards, its upper-stage engines having failed to ignite.

Read more about the tragic end of the Phobos-Grunt mission here.

After many attempts to communicate with the stranded spacecraft, Phobos-Grunt re-entered the atmosphere and impacted on January 15. Best estimates place the impact site in the Pacific Ocean off the coast of southern Chile.

The failed mission also included a Chinese orbiter and a life experiment from The Planetary Society.

Russia is offering ESA the use of a Proton launch vehicle for inclusion into the ExoMars mission, now that the U.S. has canceled its joint participation and Atlas carrier. Roscomos and ESA are scheduled to discuss the potential partnership in February.

(News via RIA Novosti)

*Phonetic pronunciation for “one more time.” Thanks to my friend Dima for the Russian lesson!

Posted on by Jason Major

Help Astronomers Measure the Solar System!

The orbit of asteroid 433 Eros brings it close to Earth on Jan. 31. (www.astronomerswithoutborders.org)

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As the bright Mars-crossing asteroid 433 Eros makes its closest approach to Earth since 1975, astronomers around the globe are taking the opportunity to measure its position in the sky, thereby fine-tuning our working knowledge of distances in the solar system. Using the optical principle of parallax, whereby different viewpoints of the same object show slightly shifted positions relative to background objects, skywatchers in different parts of the world can observe Eros over the next few nights and share their images online.

The endeavor is called the Eros Parallax Project, and you can participate too!

433 Eros' path from jan. 30 - Feb. 1, 2012. (transitofvenus.nl)

Discovered in 1898, Eros was the largest near-Earth asteroid yet identified. Its close and relatively bright oppositions were calculated by astronomers of the day and used, along with solar transits by Venus (one of which, if you haven’t heard, will also occur this year on June 5!) to calculate distances in the inner solar system.

Having both events take place within the same year offers today’s astronomers an unparalleled opportunity to obtain observational measurements.

Through the efforts of the Astronomers Without Borders organization, along with Steven van Roode and Michael Richmond from the Transit of Venus project, anyone with moderate astrophotography experience can participate in the observation of Eros and share their photos via free online software.

Using the data gathered by individual participants positioned around the world, each with their own specific viewpoints, astronomers will be able to precisely measure the distance to Eros.

The more accurately that distance is known, the more accurately the distance from Earth to the Sun can be calculated – via the orbital mechanics of Kepler’s third law.

The tumbling motion of elongated 33-km-long Eros creates a changing brightness. (via transitofvenus.nl)

The last time such a bright pass of Eros occurred was in January of 1931. Observations of the asteroid made at that time allowed astronomers to calculate a solar parallax of 8″ .790, the most accurate up to that time and the most accurate until 1968, when data acquired by radar measurements gave more detailed measurements.

In many ways the 2012 close approach by Eros – astronomically close, but still a very safe 16.6 million miles (26.7 million km) away – will allow for a re-eneactment of the 1931 event… with the exception that this time amateur skywatchers will also contribute data, instantly, from all over the world!

One has to wonder…when Eros comes this close again in 2056, what sort of technology will we use to watch it then…

Find out more about the Eros Parallax Project and how to participate here.

And be sure to check out the article about the project on Astronomers Without Borders as well.

Posted on by Nancy Atkinson

The Workings of our Solar System Creates Beautiful Musical Palindrome

If you like math, music and space (separately or in any combination) you’re gonna love this. Musician Daniel Starr-Tambor has created a song by assigning each planet a note and speeding up the orbital periods of the planets where 2 seconds represents one Earth year, with a note playing for each orbit. But this isn’t just any typical song; it ends up being a musical palindrome, which means it can be played the same both forwards and backwards … that is, if you lived long enough to play to the end of the song. At the accelerated speeds of the Solar System, Starr-Tambor estimates it would continue without repetition for over 532.25 septendecillion years (5.3225 X 10 56). And with more than 62 vigintillion (6.2 X 10 64) individual notes, this composition, called “Mandala,” is the longest musical palindrome in existence.

Back in the 17th century composers like J.S. Bach created musical palindromes (mostly to show off!) and Starr-Tambor pays homage to Bach by choosing the precise position of the Solar System at the moment of Bach’s birth, viewed from the perspective of the Sun as it faces the constellation Libra, “so that each note chronicles his birthday on every planet.”

That’s just cool.
Continue reading “The Workings of our Solar System Creates Beautiful Musical Palindrome”

Posted on by Jason Major

Does Earth Have Many Tiny Moons?

This radar image of asteroid 2005 YU55 was obtained on Nov. 7, 2011. Credit: NASA/JPL/Caltech.

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Look up in a clear night sky. How many moons do you see? Chances are, you’re only going to count to one. Admittedly, if you count any higher and you’re not alone, you may get some funny looks cast in your direction. But even though you may not be able to actually see them, there may very well be more moons out there orbiting our planet.

For the time being, anyway.

Today, Earth has one major moon in orbit around it. (Technically the Earth-Moon system orbits around a common center of gravity, called the barycenter, but that’s splitting hairs for the purpose of this story.) At one time Earth may have had two large moons until the smaller eventually collided into the larger, creating the rugged lump we now call the farside highlands. But, that was 4 billion years ago and again not what’s being referred to here.

Right now, at his moment, Earth may very well have more than the one moon we see in the night sky. Surprise.

Of course, it would be a very small moon. Perhaps no more than a meter across. But a moon nonetheless. And there could even be others – many others – much smaller than that. Little bits of solar system leftovers, orbiting our planet even farther out than the Moon we all know and love, coming and going in short-lived flings with Earth without anyone even knowing.

This is what has been suggested by researcher Mikael Granvik of the University of Helsinki in Finland. He and his colleagues have created computer simulations of asteroids believed to be occupying the inner solar system, and what the chances are that any number of them could be captured into Earth orbit at any given time.

Orbit of 2006 RH120, a confirmed TCO identified in 2006.

The team’s results, posted Dec. 20 in the science journal Icarus, claim it’s very likely that small asteroids would be temporarily captured into orbit (becoming TCOs, or temporarily captured objects) on a regular basis, each spending about nine months in up to three revolutions around Earth before heading off again.

Some objects, though, might hang around even longer… in the team’s simulations one TCO remained in orbit for 900 years.

“There are lots of asteroids in the solar system, so chances for the Earth to capture one at any time is, in a sense, not surprising,” said co-author Jeremie Vauballion, an astronomer at the Paris Observatory.

In fact, the team suspects that there’s most likely a TCO out there right now, perhaps a meter or so wide, orbiting between 5 and 10 times the distance between Earth and the Moon. And there could be a thousand smaller ones as well, up to 10 centimeters wide.

So if these moons are indeed out there, why don’t we know about them?

Put simply, they are too small, too far, and too dark.

At that distance an object the size of a writing desk is virtually undetectable with the instruments we have now.. especially if we don’t even know exactly where to look. But in the future the Large Synoptic Survey Telescope (LSST) may, once completed, be able to spot these tiny satellites with its 3200-megapixel camera.

Once spotted, TCOs could become targets of exploration. After all, they are asteroids that have come to us, which would make investigation all the easier – not to mention cheaper – much more so than traveling to and back from the main asteroid belt.

“The price of the mission would actually be pretty small,” Granvik said. And that, of course, makes the chances of such a mission getting approved all the better.

Read more on David Shiga’s article on New Scientist here.

The team’s published paper can be found here.