Asymmetrical Shape of Heliosphere Raises Questions

By Walter Cruttenden, July 7, 2008

Ever since the Voyager 2 data confirmed the nonsymmetrical shape of the solar system scientists have pondered its cause (i). In summary, the edge of the heliosphere (the place where the solar wind slows to sub sonic speeds) appears to be 1.2 billion kilometers shorter on the south side of the solar system (and in the general direction of the winter solstice, the direction of Voyager 2), than it is on the edge of the planetary plane (where Voyager 1 exited approximately a year earlier). This indicates the heliosphere is not a sphere at all but a bullet shape. More data is required to determine the exact shape in all directions.

The initial explanation was there must be some sort of gas cloud pressing against one side of our solar system. While this hypothesis is plausible there is another possibility that deserves consideration; stellar wind.

The sun’s solar winds are primarily driven by its magnetic field. When magnetic storms arise on the sun it produces coronal mass ejections (CME’s), which are like waves or ripples on the solar wind. The solar wind is constantly pushing on the daylight side of the earth’s magnetosphere squashing it in a pattern similar to the way the sun’s magnetic field seems to be squashed where Voyager 2 exited the solar system. Thus it is possible that the dented solar system might be due to the same type of cause; stellar winds from a not too distant star.

Some indication of this might reside in the data recently received by NASA’s sun-focused STEREO spacecraft. The twin STEREO spacecraft were launched in 2006 into earth’s orbit about the sun to obtain stereo pictures of the sun’s surface and to measure magnetic fields and ion fluxes associated with solar explosions. Between June and October 2007, the STEREO spacecraft detected atoms “originating from the same spot in the sky: the shock front and the heliosheath beyond, where the sun plunges through the interstellar medium”, and found “energetic neutral particles from beyond the heliosphere” that are moving toward the sun (ii). While this might be due to other causes such as “charge exchange between hot ions and neutral atoms” as hypothesized by scientists at UC Berkeley, it may also indicate the source of the asymmetrical solar system is due to the stellar wind from another star rather than an interstellar gas cloud. More data is needed and should be forthcoming with the pending launch of the Interstellar Boundary Explorer (IBEX), due to begin receiving data some time in the next year.

(i) Science Daily, Voyager 2 Proves Solar System is Squashed, December 13, 2007
(ii) E Science News, First Images of Solar System’s Invisible Frontier, July 2, 2008

Binary Research Institute.

New Tunguska Crater Found?

Jul 05, 2007

A team of Italian scientists has announced seismic evidence of what could be meteor fragments beneath Lake Cheko in Siberia–the first “solid evidence” of a Tunguska asteroid.

Lake Cheko in the Siberian region of Tunguska has recently emerged as a candidate for an “impact site” linked to the famous Tunguska explosion of 1908. Credit: / University of Bologna

On June 30, 1908, a massive explosion detonated in the skies over Tunguska in northern Siberia. The resulting shock wave flattened some 60 million trees across 2000 square kilometers. The blast was heard hundreds of miles away and the cloud of dust colored the skies of the Northern Hemisphere for months afterwards.

The first expedition to investigate the region could not locate any sign of an impact event, nor did it recover any meteoric fragments. A later expedition, however, did uncover magnetite globules and various forms of silicate globules embedded in the earth and in the trees.

Most scientists eventually settled on either an icy comet explosively vaporized before reaching the surface, or a small rocky asteroid exploding in the atmosphere and leaving no appreciable fragments. But the absence of definitive evidence for an impact invited many exotic theories–ranging from “mirror-matter” or a tiny “quantum black hole,” to an exploding alien craft or a Nikola Tesla experiment gone awry.

In past discussions of the Tunguska event, our Picture of the Day editors have suggested electric discharge between a small comet or asteroid and the Earth. That suggestion was based on a wide variety of recorded physical effects and the testimony of human witnesses.

More recently, however, a team of Italian researchers has suggested that the 164-foot deep Lake Cheko, five miles northwest of the epicenter of the blast, could be the site of an impact by a meteor or a fragment of the body responsible for the devastating Tunguska event.

The team reported that 3D sonar images of the lake’s bottom indicate that it is funnel-shaped, something that might be expected of both an impactor and an electric discharge. Using seismic detectors, the University of Bologna scientists discovered an area of greater density beneath the lake, noting that this could indicate the remains of a meteor. “When we looked at the bottom of the lake, we measured seismic waves reflecting off of something,” said Giuseppe Longo, a physicist at the University of Bologna in Italy and co-author of the study. “Nobody has found this before. We can only explain that and the shape of the lake as a low-velocity impact crater.”

According to a report on the web site, however, some physicists are skeptical about the small size of the Lake Cheko crater. “We know from the entry physics that the largest and most energetic objects penetrate deepest,” said David Morrison, an astronomer with NASA’s Ames Research Center. Morrison wondered aloud why only a fragment of the main explosion would reach the ground to make a relatively small crater, while the greater portion would not create a larger main crater.

But Alan Harris, a planetary scientist at the Space Science Institute, points out that, in 1947, the Russian Sikhote-Alin meteorite created 100 small craters. Some were 20 meters (66 feet) across. A site in Poland also exists, he explained, where a large meteor exploded and created a series of small lakes. “If the fragment was traveling slowly enough, there’s actually a good chance [the Italian team) will unearth some meteorite material,” Harris said.

The researchers will return to Tunguska this summer with plans to drill beneath the bottom of Lake Cheko, hoping to find a meteorite. From an Electric Universe perspective, if the Tunguska explosion was the result of an electric discharge, a meteor fragment may indeed be found, pointing to the source of the discharge. But more likely, the increased density beneath the lake could be the signature of the electric arc that excavated the depression, producing the fused sands and soils of a fulgurite.

By Stephen Smith

New Tunguska Crater Found?.

Mysterious Objects at the Edge of the Electromagnetic Spectrum

March 16, 2012: The human eye is crucial to astronomy. Without the ability to see, the luminous universe of stars, planets and galaxies would be closed to us, unknown forever. Nevertheless, astronomers cannot shake their fascination with the invisible.

Outside the realm of human vision is an entire electromagnetic spectrum of wonders. Each type of light–­from radio waves to gamma-rays–reveals something unique about the universe. Some wavelengths are best for studying black holes; others reveal newborn stars and planets; while others illuminate the earliest years of cosmic history.

NASA has many telescopes “working the wavelengths” up and down the electromagnetic spectrum. One of them, the Fermi Gamma-Ray Telescope orbiting Earth, has just crossed a new electromagnetic frontier.

A new ScienceCast video takes viewers on a trip to the edge of the electromagnetic spectrum, where mysterious objects are puzzling astronomers.

“Fermi is picking up crazy-energetic photons,” says Dave Thompson, an astrophysicist at NASA’s Goddard Space Flight Center. “And it’s detecting so many of them we’ve been able to produce the first all-sky map of the very high energy universe.”

“This is what the sky looks like near the very edge of the electromagnetic spectrum, between 10 billion and 100 billion electron volts.”

The light we see with human eyes consists of photons with energies in the range 2 to 3 electron volts. The gamma-rays Fermi detects are billions of times more energetic, from 20 million to more than 300 billion electron volts. These gamma-ray photons are so energetic, they cannot be guided by the mirrors and lenses found in ordinary telescopes. Instead Fermi uses a sensor that is more like a Geiger counter than a telescope. If we could wear Fermi’s gamma ray “glasses,” we’d witness powerful bullets of energy – individual gamma rays – from cosmic phenomena such as supermassive black holes and hypernova explosions. The sky would be a frenzy of activity.

An artist’s concept of giant ‘Fermi bubbles’ emerging from the heart of the
Milky Way.

Before Fermi was launched in June 2008, there were only four known celestial sources of photons in this energy range. “In 3 years Fermi has found almost 500 more,” says Thompson.

What lies within this new realm?

“Mystery, for one thing,” says Thompson. “About a third of the new sources can’t be clearly linked to any of the known types of objects that produce gamma rays. We have no idea what they are.”

The rest have one thing in common: prodigious energy.

“Among them are super massive black holes called blazars; the seething remnants of supernova explosions; and rapidly rotating neutron stars called pulsars.”
And some of the gamma rays seem to come from the ‘Fermi bubbles’ – giant structures emanating from the Milky Way’s center and spanning some 20,000 light years above and below the galactic plane.

Exactly how these bubbles formed is another mystery.

Now that the first sky map is complete, Fermi is working on another, more sensitive and detailed survey.

“In the next few years, Fermi should reveal something new about all of these phenomena, what makes them tick, and why they generate such ‘unearthly’ levels of energy,” says David Paneque, a leader in this work from the Max Planck Institute in Germany.

For now, though, there are more unknowns than knowns about “Fermi’s world.”

Says Thompson: “It’s pretty exciting!”

Authors: Dauna Coulter, Dr. Tony Phillips | Credit: Science@NASA

Mysterious Objects at the Edge of the Electromagnetic Spectrum – NASA Science.