Giant asteroid Vesta ‘resembles planet’

23 March 2012 Last updated at 08:15 ET
By Paul Rincon
Science editor, BBC News website, The Woodlands, Texas


Dawn’s view of the south pole of the giant asteroid Vesta

The giant asteroid Vesta possesses many features usually associated with rocky planets like Earth, according to data from a Nasa probe.

Vesta has been viewed as a massive asteroid, but after studying the surface in detail, scientists are describing it as “transitional”.

The Dawn spacecraft has been orbiting Vesta – one of the Solar System’s most primitive objects – since July 2011.

They have documented many unexpected features on its battered surface.

Mission scientists presented their latest results at the Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.

Dawn’s principal investigator, Christopher T Russell, told the meeting that the science team found it hard not to refer to the object as a planet.

He said the rounded asteroid showed evidence of geological processes that characterise rocky worlds like Earth and the Moon.

Getting hammered

Vesta is the second most massive of the asteroids, measuring some 530km (330mi) in diameter. It is dominated by a huge crater called Rheasilvia and bears many other scars left by the hammering it has received at the hands of other asteroid belt denizens.

One important transitional feature of Vesta can be found in its topography, or elevation. Vertical elevation on the Moon or Mars might reach tens of kilometres, but these objects are also very large.

“This means the topography is about 1% of the radius,” Dr Ralf Jaumann, from the German Aerospace Center (DLR), told BBC News, “If you go to Vesta, it is 15%, and if you go to the largest outer asteroid – Lutetia – it is 40%.”

In short, this mathematical relationship between topography and radius (half an object’s diameter), puts Vesta in an intermediate position between small asteroids and rocky planets.

Another aspect concerns the way its surface has been modified, or “processed”, by the many collisions. This is evident in dark material that can be seen in images of its terrain.

The dark material seems to be related to impacts and their aftermath. Scientists think carbon-rich asteroids could have hit Vesta at speeds low enough to produce some of the smaller deposits without blasting away the surface.

Higher-speed asteroids could also have collided with Vesta’s surface and melted the volcanic basaltic crust, darkening existing surface material.

Scientists are confident there has been volcanism on the asteroid during its history. This is because there are hundreds of pieces of Vesta sitting in museums around the world.

They form a particular class of meteorite called the HEDs; more of these objects have fallen to Earth than all the meteorites from the Moon and Mars put together. Studies of HED meteorites have revealed telling chemical signatures of volcanic activity.

Major cover-up

Dave Williams, from Arizona State University, told BBC News: “We know [from the HED meteorites] there were lava flows at some point in history, so I expected there to be at least a few lava flows, maybe a few channels, shields or cones. Looking at all the images in places that have been illuminated thus far, we don’t see any evidence of that.

“That’s because of all the impact processing over Solar System history. It has destroyed all the evidence.”

Mission scientist Brett Denevi, from Johns Hopkins University Applied Physics Laboratory in Maryland, explained why she thought some of the collisions that have pounded Vesta were intense enough to melt its surface.

Referring to observations of a crater called Marcia, in Vesta’s northern hemisphere, Dr Denevi commented: “We think what we’re seeing here is at least a portion of this target rock has melted and flowed. The impact velocities were high enough – at least in this one case.”

She added: “Impact melt hasn’t really been observed on asteroids before. It wasn’t really expected because the speed of collisions in the asteroid belt are pretty low compared with the inner Solar System. So it wasn’t known whether you’d have enough energy to melt the target rock.”

Dawn is set to depart Vesta for an even bigger object – the spherical “dwarf planet” Ceres – in August for an arrival in 2015.

Paul.Rincon-INTERNET@bbc.co.uk and follow me on Twitter

BBC News – Giant asteroid Vesta ‘resembles planet’.

Exact Date Of Deluge Established By Scientists

MONDAY, 02 APRIL 2012 11:48

The increasing number of natural disasters worldwide has become the subject of much debate and forecasts among scientists. The last global catastrophic event on a planetary scale which humanity still remembers thanks to the Old Testament is the Flood. A fundamental book by famous scientists Victor Khain and Elchin Khalilov titled “Cyclicity of geodynamic processes: its possible nature” refers to amazing geological facts that reveal the exact date of the Flood. Below is quoted a small part of the section describing the geological interpretation of this event.

Earthquakes, tsunamis, large landslides and rock falls, volcanic eruptions, particularly violent hurricanes are certainly geological hazards. They take thousands, occasionally tens and even hundreds of thousands of human lives, and it is not surprising that a special international program is dedicated to forecasting hazardous situations and possible mitigation of their consequences.

Evidently, the most violent catastrophe in the recent history of Earth has been the one described in the Old Testament as the Deluge. For a long time, until the appearance in the 1820s of works by English geologists W. Buckland and A. Sedgwick, this event was regarded as a real one and the entire history of Earth was divided into two eras: before and after the Deluge. However, the views of “diluvianists” as they were called (“diluvio” is Latin for flood) were later rejected and even ridiculed. Nowadays it turns out that there is much truth in the Old Testament writings. Austrian scientists from the Vienna University Edith Cristian Tollman and Alexander Tollman have published a serious research (Cristian-Tollman and Tollman) in which, based on analysis of different sources, the precise date of this event is established: September 23, 9545 ВС, i.e., the beginning of the Holocene.

The event itself interpreted as collision of Earth with a comet main fragments of which fell into the ocean triggered an earthquake of enormous proportion, violent volcano eruptions, huge tsunami waves, global-scale hurricanes and rainfall, sharp temperature rise, forest fires, and overall darkening followed by cooling (of the “nuclear winter” type). The Deluge caused extinction of a number of species of the then-existing terrestrial fauna including mammoths, while primitive humans survived only in caves. One of evidences of that event is the rain-like precipitation of rounded tektites over a vast area covering Asia, Australia, Southern India, and Madagascar. The age of tektite-bearing layers in Vietnam (about 10 thousand years, Izokh, 1991) coincides with the timing of the “flood” established by the Tollmans according to other data: annual tree rings, sharp increase in the acid content in the Greenland ice cover, time of mammoth extinction in Siberia.

There is every reason to suggest that similar hazards triggered by collisions with comets (like the Tunguska event) or by falling of large meteorites (asteroids) have repeatedly occurred in earlier geological era, causing “great extinctions” of fauna and flora. The list of natural disasters of purely terrestrial origin should be complemented with those related to the space-earth interactions.

So, the data on current geological processes, both endogenic and exogenic, shows that they develop in a continuous-intermittent manner and their slow smooth course is interrupted by sharp accelerations, the effect of which during short time intervals is much greater than that of slow changes occurring during much longer time intervals separating those accelerations*

_____________________________________________________
* Khain V.E., Khalilov E.N. CYCLICITY IN GEODYNAMIC PROCESSES: ITS POSSIBLE NATURE – Moscow: Scientific World, 2009. – 520 p. ISBN 978-5-91522-082-8

Exact Date Of Deluge Established By Scientists.

Huge Sunquakes Triggered by Solar Eruptions

Massive solar wind bursts and magnetic fields can cause ripples on sun’s surface

By Kat Piper
Epoch Times Staff
Created: March 30, 2012
Last Updated: April 4, 2012

Massive bursts of solar wind and magnetic fields from the Sun can cause huge sunquakes, according to new UK research.

The results of the study, led by University College London’s Mullard Space Science Laboratory, are being presented by Dr Sergei Zharkovat at the National Astronomy Meeting 2012 in Manchester on Friday, March 30.

Research over the last 10 years has shown that sunquakes can be produced when solar flares—huge explosions of energy in the Sun’s atmosphere—impact and travel into the Sun. The quakes appear as circular ripples on the surface of the Sun.

The new study shows that eruptions of charged particles and magnetic fields known as Coronal Mass Ejections (CMEs) are also able to produce sunquakes.

“Sunquakes are generated by solar flares, when enormous amounts of energy are released high up in the solar atmosphere. Most of the energy goes up into interplanetary space, but a fraction of this energy travels to the Sun’s surface creating a sonic boom that causes the solar interior to oscillate and produce the ripples,” explained Zharkov in an email.

“I sometimes think of sunquakes as thunder to the flare’s lightning, except imagine a lightning over an ocean that is so strong that it creates a tsunami.”

The researchers studied an eruption that took place on Feb. 15, 2011. They found that sunquakes 1,000 times more powerful than the March 2011 Japanese earthquake were triggered at two ends of the erupting rope of magnetic field. The sudden expansion of the magnetic field as it erupts is thought to play a part in the generation of the sunquakes.

The eruption travelled through our solar system at around 600 kilometres per second (1.34 million miles per hour) towards Earth, causing a geomagnetic storm and aurora when it hit the Earth’s atmosphere.

It is for this reason that study of sunquakes is of interest, especially as solar activity is predicted to increase and peak in 2013.

“Sunquakes themselves do not have [an] impact on Earth as they are acoustic waves travelling inside the Sun. But flares and, accompanying them, Coronal Mass Ejections that we have shown play an important role in generating sunquakes, can and do impact Earth,” Zharkov said.

“Sunquakes now form an integral part for our search for understanding of flare and CME phenomena.”

Flares and CMEs have a direct impact on space weather, so understanding how they form could help in predicting when they are going to occur and planning for possible geomagnetic storms, which can affect satellites and radio and GPS equipment on Earth.

But sunquakes are relatively rare, explained Zharkhov. “Known sunquakes were all generated by string solar flares (X and M class), which occur only during the active part of an [11-year] Solar Cycle. However, only a small fraction of such flares produce sunquakes,” he said.

“There is also a chance, however, that sunquakes are more common than we think; it’s just that our means of detecting them are not yet up to scratch.”

Until recently, observation of sunquakes had been hampered by availability of data. “With the (relatively) new NASA’s Solar Dynamics Observatory satellite providing us with practically continuous high resolution and high cadence observations of the Sun, this problem is now solved,” Zharkov said.

Much like geologists use earthquakes to understand the internal structure of our planet, future research will be focused on using sunquakes to learn more about the internal processes of the Sun, said Zharkov. As scientists still don’t fully understand how sunquakes are generated, research will also continue to look for physical explanations of this solar phenomenon.

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Huge Sunquakes Triggered by Solar Eruptions | Space & Astronomy | Science | Epoch Times.