Tag: solar system

Was Gold Brought to Earth by a Pluto-Sized Planet Crasher?

By Andrew Moseman | December 10, 2010 11:08 am

gold_barThe gold ring around your finger may symbolize “till death do us part” for you, but for scientists, it poses a problem.

That shiny band probably cost a small fortune at the jewelry store, but gold is actually abundant on the Earth’s surface (which helps explain why it’s the ideal form of money). The difficulty is, when scientists apply what they know about how the solar system formed, it’s hard to explain how all that gold (and other precious metals that bond easily to iron, like palladium and platinum) got into the Earth’s crust, where bling-loving humans could get at it. A new study in Science sets forth an explanation: In the Earth’s younger days, impacts by huge objects—perhaps even one as big as Pluto—may have brought it here.

To explain this theory, let’s start with the most dramatic impact in our planet’s history: the one that formed the moon and re-melted the solidifying Earth in the process.

Moon rocks brought back during the Apollo missions led to the now widely accepted theory that the moon formed when a Mars-size object crashed into early Earth. Energy from the impact would have spurred the still forming Earth to develop its mostly iron core. When this happened, iron-loving metals should have followed molten iron down from the planet’s mantle and into the core. But we know that gold and other iron-lovers are found in modest abundances in Earth’s mantle. [National Geographic]

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Japan's Spacecraft Misses Venus, but Gets Another Chance—in 6 Years

By Andrew Moseman | December 8, 2010 9:33 am

akatsukiWhen we left Akatsuki last night, the Japanese spacecraft’s operators were waiting with fingers crossed, hoping their $300 million baby could still successfully enter orbit of Venus even after things started to go wrong. Overnight our time, the bad news came in: Akatsuki missed the target, and won’t have another shot at it for six more years.

Things first started to get hairy when Akatsuki, after traveling more than six months to the second planet, lost contact with Earth for longer than expected—an hour and a half as opposed to the 22 minutes it was supposed to be out of reach as it passed behind the planet.

JAXA scientists managed to re-establish communication with the spacecraft, the newspaper Japan Today reported. But during a press conference Tuesday (Dec. 7), JAXA officials said Akatsuki sped past Venus, failing to insert into orbit, according to Japan Today. “I’m sorry that we failed to meet the expectations of the public,” Japan Today quoted Masato Nakamura, Akatsuki project manager, as saying during the press conference. [Space.com]

Having made their apologies, the Akatsuki researchers are investigating exactly how the craft faltered. And they’re beginning the long wait for another chance—in six years the craft should have another shot at entering orbit.

If it misses the next window in six years, Akatsuki, which was launched into space May 20, risks entering the same graveyard as its predecessor Nozomi, the Japanese spacecraft launched in 1998 to explore Mars. The probe was put to rest after five years riddled with technical problems. [Wall Street Journal]

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Image: JAXA

MORE ABOUT: japan, JAXA, solar system, Venus

Japan's Spacecraft Reaches Venus, But Did It Miss Its Orbital Path?

By Andrew Moseman | December 7, 2010 5:32 pm

akatsukiJapan’s new spacecraft has reached Venus; that much we know. But today Akatsuki left its creators hanging when it lost contact with home for longer than expected, and Japan’s space agency JAXA is now trying to make sure the $300 million mission reached the orbit they intended for it above the second planet from the sun.

When Akatsuki arrived at Venus and swung around the backside, it was expected to lose contact with Earth for a little over 20 minutes. Instead, it couldn’t reach JAXA for an hour and a half, sending the space scientists scrambling to make sure nothing went awry.

Communications with the probe were eventually resumed, but it’s currently unclear whether Akatsuki successfully entered orbit around Venus. “It is not known which path the probe is following at the moment,” JAXA official Munetaka Ueno told the AFP news agency. “We are making maximum effort to readjust the probe.” [National Geographic]

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Photo: Comet Hartley 2 Travels With a Posse of Snowballs

By Eliza Strickland | November 19, 2010 3:28 pm

Phil Plait has the report on NASA’s latest pictures from the flyby of Hartley 2, which reveal that the comet is surrounded by a blizzard of snow and ice:

Wow! Most of those dots are not stars: they are actual snowballs, frozen matter that has been ejected by the comet itself! They range in size from a few centimeters to a few dozen across, so they really are about the size of snowballs you’d use in a snowball fight… or to make a snowman. But I wouldn’t recommend it: a lot of that material is not frozen water, it’s actually frozen carbon dioxide, or dry ice.

Find out what else we’ve learned about Hartley 2 and see more photos at Bad Astronomy.

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Bad Astronomy: Amazing Close-Ups of Comet Hartley 2!
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Bad Astronomy: Ten Things You Don’t Know About Comets

Image: NASA / JPL-Caltech / UMD


New Bragging Rights for Pluto? It May Be the Biggest Dwarf Planet

By Andrew Moseman | November 8, 2010 4:47 pm

erisbigPluto’s dinky diameter wasn’t the official reason it was demoted from the planetary club back in 2006, but symbolically, size was the last straw. When Caltech astronomer Mike Brown spotted the object we now call Eris back in 2005 and astronomers figured it to be larger than Pluto, the former ninth planet’s fate was sealed. Now Pluto’s reclassification as a “dwarf planet” and the subsequent public outcry is behind us, but new research suggests that the former planet’s symbolic death knell—Eris’ size advantage—was wrong.

The argument has been rekindled by astronomers who just completed detailed viewings of Eris from observatories high in the Chilean Andes. According to Bruno Sicardy of the Paris Observatory, Eris must be no wider than 1,454 miles, while the accepted value for Pluto’s diameter is 1,456.5 miles. And because of the uncertainty of measuring diameter of such a distant object, Kelly Beatty at Sky & Telescope says, Eris’ official size could decease another 30 miles or more after astronomers analyze more of this data.

Images taken in December 2005 by Brown and others with the Hubble Space Telescope indicated a diameter of 1,500 miles (2,400 km), just 5% larger than Pluto’s. But the true size remained uncertain because even Hubble’s supersharp gaze is only barely able to resolve Eris’s disk. (Remember: it’s some 9 billion miles from the Sun, twice as far away as Pluto.) [Sky & Telescope]

This month, however, the window of opportunity opened for astronomers. Eris passed directly in front of a star, which allowed them to more accurately gauge its size.

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Comet Flyby Yields Close-ups of the Lumpy, Icy Hartley 2

By Eliza Strickland | November 4, 2010 12:31 pm

Hartley2This morning, NASA’s EPOXI mission whizzed by the comet Hartley 2, coming as near as 450 miles to the comet at 8 a.m. and snapping pictures all the while. The icy comet is less than a mile in diameter and has an irregular shape that one NASA researcher recently described as “a cross between a bowling pin and a pickle.”

The images are already streaming in: Head to Bad Astronomy for more pictures and a discussion of what these snapshots tell us about Hartley 2.

This is the second cometary encounter for this spacecraft–under a previous mission called Deep Impact the spacecraft sent an impactor hurtling into the comet Tempel 1, allowing the craft to photograph the excavated debris and the impact crater.

Related Content:
80beats: Holy Hartley 2! What to Know About NASA’s Comet Flyby
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Bad Astronomy: Ten Things You Don’t Know About Comets
DISCOVER: NASA Takes a Wild Comet Ride



Holy Hartley 2! What to Know About NASA's Comet Flyby

By Andrew Moseman | October 26, 2010 4:59 pm

hartley2On November 4, NASA’s mission EPOXI will make a flyby less than 450 miles from the comet Hartley 2. Here’s what to know about this dirty snowball.

1. It’s a frequent visitor.

Malcolm Hartley discovered this namesake comet 24 years ago, and it’s returned to swing around the sun a few times since.

Like the famous Halley’s Comet, Comet Hartley 2 is a periodic comet that follows a years-long loop around the sun. It takes 6.46 years to complete one circuit, compared with Halley’s 75.3 years. [Christian Science Monitor]

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The Edge of the Solar System Is a Weird and Erratic Place

By Andrew Moseman | October 1, 2010 2:51 pm

IBEXThe edge of the solar system is not some static line on a map. The boundary between the heliosphere in which we live and the vastness of interstellar space beyond is in flux, stretching and shifting more rapidly than astronomers ever knew, according to David McComas.

McComas and colleagues work with NASA’s Interstellar Boundary Explorer (IBEX), a satellite orbiting the Earth with its eye turned to the edge of the heliosphere—the bubble inflated by the solar wind that encapsulates the solar system and protects us from many of the high-energy cosmic rays zinging across interstellar space. This week in the Journal of Geophysical Research, the team published the results of IBEX’s second map of the region, and found that its makeup has changed markedly over the span of just six months. Says McComas:

“If we’ve learned anything from IBEX so far, it is that the models that we’re using for interaction of the solar wind with the galaxy were just dead wrong.” [National Geographic]

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Homey-Looking Alien Star System May Host 7 Planets

By Andrew Moseman | August 25, 2010 10:53 am

NewStarSystemIn August 2006, Pluto received its official demotion to dwarf planet status, taking our solar system down to eight planets. In August 2010, exoplanet hunters say they’ve found a haul of new worlds around a single star; that alien solar system may have seven known planets, meaning the system could be more like our home system than any ever discovered. And one of those worlds could be the smallest exoplanet ever found, too.

The star these planets orbit is called HD 10180, and it lies 127 light years from here. Astronomers at the European Southern Observatory in Chile used a spectrograph called HARPS to track tiny variations in the starlight caused by the pull of the planets.

It found clear evidence for five giant planets similar in size to Uranus or Neptune in our own solar system. But there were also tantalising signs that two other planets are also present, one of which would be the smallest, or least-massive, yet found orbiting another star [Christian Science Monitor].

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Found: One of Neptune's Asteroid Stalkers

By Joseph Calamia | August 13, 2010 1:48 pm

neptuneAstronomers have confirmed it: Neptune has a stalker. They have spotted, for the first time, an asteroid follower that keeps a fairly constant distance behind the planet in its orbit around the sun. And there may be many more.

Asteroid 2008 LC18 can’t help itself. It’s caught in a balancing game between the gravitational tug of the sun and Neptune, and effects from its whirling course. The conflicting tugs cause the asteroid not to orbit Neptune or crash into it, but instead to follow the planet from a little distance behind (about 60 degrees on its path).

Neptune has five of the these pits–called Lagrangian points (see diagram below the fold)–but the spots ahead and behind the planet, researchers say, are best for asteroid-trapping, since the hold is particularly stable in these places. Researchers have previously spotted several asteroids in front of the planet (again by about 60 degrees), but this is the first time they’ve found one following it. The findings appeared online yesterday in Science.

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CATEGORIZED UNDER: Physics & Math, Space

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