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Swirling Neptune



By tracking atmospheric features on Neptune, a UA planetary scientist has accurately determined the planet's rotation, a feat that had not been previously achieved for any of the gas planets in our solar system except Jupiter.
In this animation, the viewer takes the perspective of an object circling Neptune matching its rotational speed, much like a geostationary satellite hovering above the same spot. Only then does the giant gas planet reveal the movements of its features relative to each other, often in opposite directions.
Copyright: E. Karkoschka/University of Arizona



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Clocking Neptune's Spin

By tracking atmospheric features on Neptune, a UA planetary scientist has accurately determined the planet's rotation, a feat that had not been previously achieved for any of the gas planets in our solar system except Jupiter.
A day on Neptune lasts precisely 15 hours, 57 minutes and 59 seconds, according to the first accurate measurement of its rotational period made by University of Arizona planetary scientist Erich Karkoschka.
His result is one of the largest improvements in determining the rotational period of a gas planet in almost 350 years since Italian astronomer Giovanni Cassini made the first observations of Jupiter's Red Spot.

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Title: Last giant impact on the Neptunian system. Constraints on oligarchyc masses in the trans-Saturnian region
Author(s): M.G. Parisi, L. del Valle

Stochastic impacts by large bodies are, at present, the usually accepted mechanisms able to account for the obliquity of the ice giants. We attempt to set constraints on giant impacts as the cause of Neptune's current obliquity in the framework of modern theories. We also use the present orbital properties of the Neptunian irregular satellites (with the exception of Triton) to set constraints on the scenario of giant impacts at the end of Neptune formation. We model the angular momentum transfer to proto-Neptune and the impulse transfer to its irregular satellites by the last stochastic collision (GC) between the protoplanet and an oligarchic mass at the end of Neptune's formation. We obtain that an impactor mass greather than 4 Earth masses is not possible since it cannot reproduce the present rotational properties of the planet, unless the impact parameter of the collision were very small. On the other hand, if the impactor mass was greather than 1.4 Earth masses, the present Neptunian irregular satellites had to be formed or captured after the end of stochastic impacts. The upper bounds on the oligarchic masses (4 Earth masses from the obliquity of Neptune and 1.4 earth masses from the Neptunian irregular satellites) are independent of unknown parameters, such as the mass and distribution of the planetesimals, the location at which Uranus and Neptune were formed, the Solar Nebula initial surface mass density, and the growth regime. If stochastic impacts had occurred, these results should be understood as upper constraints on the oligarchic masses in the trans-Saturnian region at the end of ice planet formation and may be used to set constraints on planetary formation scenarios.

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On the 1st May, 1949, Nereid the second moon of the planet Neptune was discovered by Gerard Kuiper.



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On this day, in 1846, French astronomer Urbain Jean Joseph Le Verrier and British astronomer John Couch Adams discovered the planet Neptune.
The discovery was verified by German astronomer Johann Gottfried Galle.

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The rings of Neptune consist primarily of five principal rings and discovered on the 22nd August, 1989, by the Voyager 2 spacecraft.
The rings may consist of ice particles coated with silicates or carbon-based material, which most likely gives them a reddish hue.  The three main rings are the narrow Adams Ring, 63000 km from the centre of Neptune, the Le Verrier Ring, at 53000 km, and the broader, fainter Galle Ring, at 42000 km. A faint outward extension to the Le Verrier Ring has been named Lassell; it is bounded at its outer edge by the Arago Ring at 57000 km.

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Neptune in the constellation Aquarius. 00:40 UT, 3rd August, 2010.

Magnitude= 7.8mag  
Best seen from  0.7h - 2.9h
RA=21h59m52s  Dec=-12°45.4' (J2000)
Distance=29.048AU
Elongation=163° 
Diameter=2.3"

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Neptune in the constellation Aquarius, 00.50 UT, 2nd August, 2010.

Magnitude= 7.8mag   
Best seen from  0.8h - 2.9h
RA=21h59m58s  Dec=-12°44.8' (J2000)
Distance=29.053AU 
Elongation=162°  
Diameter=2.3"

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'Neptune water' soon in labs

Scientists plan to simulate conditions in lab to show exactly how water behaves in the extreme conditions that Neptune presents.
The new Facility for Antiprotons and Ion Research (FAIR) in Germany, which will be ready in 2015, will expose water molecules to heavy ion beams and thereby generate the same level of pressure on the water molecules that they experience within the very inhospitable core of Neptune.

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Cometary Impact on Neptune

Measurements performed by the space observatory Herschel point to a collision about two centuries ago

A comet may have hit the planet Neptune about two centuries ago. This is indicated by the distribution of carbon monoxide in the atmosphere of the gas giant that researchers - among them scientists from the French observatory LESIA in Paris, from the Max Planck Institute for Solar System Re-search (MPS) in Katlenburg-Lindau (Germany) and from the Max Planck Institute for Extraterrestrial Physics in Garching (Germany) - have now studied. The scientists analysed data taken by the research satellite Herschel, that has been orbiting the Sun in a distance of approximately 1.5 million kilometres since May 2009. (Astronomy & Astrophysics, published online on July 16th, 2010)
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