MPS: Cometary Impact on Neptune

[bystander]

Cometary Impact on Neptune
Max Planck Institute for Solar System Research | 16 July 2010

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

Click to view full size image

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 Research (MPS) in Katlenburg-Lindau (Germany) and from the Max Planck Institute for Extraterrestrial Physics in Garching (Germany) - have now studied. The scientists analyzed data taken by the research satellite >Herschel, that has been orbiting the Sun in a distance of approximately 1.5 million kilometers since May 2009. (Astronomy & Astrophysics, published online on July 16th, 2010)

When the comet Shoemaker-Levy 9 hit Jupiter sixteen years ago, scientists all over the world were prepared: instruments on board the space probes Voyager 2, Galileo and Ulysses documented every detail of this rare incident. Today, this data helps scientists detect cometary impacts that happened many, many years ago. The "dusty snowballs" leave traces in the atmosphere of the gas giants: water, carbon dioxide, carbon monoxide, hydrocyanic acid, and carbon sulfide. These molecules can be detected in the radiation the planet radiates into space.

In February 2010 scientists from MPS discovered strong evidence for a cometary impact on Saturn about 230 years ago (see Astronomy and Astrophysics, Volume 510, February 2010). Now new measurements performed by the instrument PACS (Photodetector Array Camera and Spectrometer) on board the Herschel space observatory indicate that Neptune experienced a similar event. For the first time, PACS allows researchers to analyze the long-wave infrared radiation of Neptune.

Image Credit: NASA

First results of Herschel-PACS observations of Neptune

• Astronomy and Astrophysics 518 L152 (Jul-Aug 2010) DOI: 10.1051/0004-6361/201014600
  arXiv.org > astro-ph > arXiv:1006.0114 > 01 June 2010

Neptune's Cold Case: Shot by a Comet 200 Years Ago?
Discovery News | Space | 20 July 2010

After some clever detective work, astronomers think Neptune was hit by a large comet... two centuries ago.

[neufer]

The Great Dark Spot, as seen from Voyager 2

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One is left with the impression that this supposed
comet of 230 years ago left behind the Great Dark Spot.

But, of course, that can't be:

<<In 1989, the Great Dark Spot, an anti-cyclonic storm system spanning 13,000 × 6,600 km, was discovered by NASA's Voyager 2 spacecraft in Neptune's southern hemisphere. The storm resembled the Great Red Spot of Jupiter. Some five years later, however, on November 2, 1994, the Hubble Space Telescope did not see the Great Dark Spot on the planet. Instead, a new storm similar to the Great Dark Spot was found in the planet's northern hemisphere.

Neptune's dark spots are thought to occur in the troposphere at lower altitudes than the brighter cloud features, so they appear as holes in the upper cloud decks. As they are stable features that can persist for several months, they are thought to be vortex structures. Often associated with dark spots are brighter, persistent methane clouds that form around the tropopause layer. The persistence of companion clouds shows that some former dark spots may continue to exist as cyclones even though they are no longer visible as a dark feature. Dark spots may dissipate when they migrate too close to the equator or possibly through some other unknown mechanism.>>

[bystander]

I thought so to when I first saw the article, but if you read them they don't even mention the Great Dark Spot.

[neufer]

I thought so to when I first saw the article, but if you read them they don't even mention the Great Dark Spot.

The true source of Neptune's Dark Spot vortex structures:

[owlice]

:: falls over laughing ::