Cosmic dance party: Tiny dwarf star influencing monster planet’s unusual orbit

……………………………………………………………..

 

Published time: 17 Dec, 2015 13:50

© NASA

 

A huge planet is having quite the party in space, dancing between its cosmic companions rather eccentrically – all thanks to a tiny dwarf star which influences its bizarre movements. The new finding makes for a rather peculiar planetary system.

Measuring about eight times the mass of Jupiter, the enormous planet was discovered in 2011. At the time of its discovery, it was found to be orbiting a sun-like star called HD 4779 with high eccentricity. That is, its movements were far from perfectly circular – the further from a circle the trajectory is, the more eccentric it is.

But the eccentric orbit led a team made up almost entirely of current and former Carnegie scientists to speculate that something else may be influencing the monster planet’s movements. They tested that theory with the Magellan adaptive optics (MagAO) instrument suite, which allowed them to take extremely high-resolution images and gave them a sharper look at the night sky than ever before. Their speculation was then confirmed.

“At the telescope, we saw the object within seconds, and that told us it had to be a dwarf star,” said lead author Timothy Rodigas in a press release. The dwarf star was tiny, measuring at only 20 percent of the mass of our sun.

 

© Carnegie Institute

Read More Here

Report of discovery of large object in far outer edges of solar system incites skeptical reactions

……………………………………………………………

 

Phys.org

December 11, 2015 by Bob Yirka report

ALMA prototype-antennas at the ALMA test facility. Credit: ESO

(Phys.org)—Two separate teams of researchers (one from Mexico, the other Sweden), have incited skepticism among the astronomy community by posting papers on the preprint server arXiv each describing a different large object they observed in the outer edges of the solar system. Both teams made their observations after reviewing data from ALMA—a cluster of radio dishes in the Chilean mountains.

One of the objects was found to be near W Aquilae in the night sky—the other adjacent to Alpha Centauri . Both groups report being skeptical at first regarding a faint glow, but monitored what they had seen nonetheless—to their surprise they found that the objects appeared to move relative to the stars behind them, which suggested they might be relatively close and that they might be orbiting the sun. Neither group was able to gain much evidence regarding the properties of the objects they had spied, because both of them were only able to make two observations, but both teams suggest there was enough data to allow for ruling out the object being an ordinary star.

The Swedish team nick-named the object they observed Gna, after a Nordic God known for its swiftness, and have told the press they had no intention of suggesting they had found the mythical Planet X which supposedly lies somewhere beyond Pluto. Instead they suggest it might be a large asteroid. The team from Mexico went a little further suggesting that the object they observed might possibly turn out to be a brown dwarf.

 

Read More Here

The annual Geminid meteor shower peaks tonight, Dec. 13-14, as Earth passes through a stream of gravelly debris from “rock comet” 3200 Phaethon

……………………………………………………………

 

by Dr. Tony Phillips.

GEMINID METEOR SHOWER–TONIGHT!

 

The annual Geminid meteor shower peaks tonight, Dec. 13-14, as Earth passes through a stream of gravelly debris from “rock comet” 3200 Phaethon. Dark-sky observers in both hemispheres could see as many as 120 meteors per hour during the dark hours between midnight and sunrise on Dec. 14th. Last night, Dec. 12-13, NASA’s all-sky meteor network detected 15 Geminid fireballs over the USA. That number will surely grow on peak night–tonight! Got clouds? Listen for Geminid echoes in the audio feed from our live meteor radar.

…………………………………………………………………………………………

Geminids meteor shower prediction: Moonless and marvelous

By Alan MacRobert

Updated 3:12 PM ET, Sat December 12, 2015

Story highlights

• Geminids meteor shower is peaking
• Geminid meteors can flash into view anywhere in the night sky

(Sky and Telescope)The nights of December 13-14 offer dark skies for a popular, underappreciated meteor display.

The Geminid meteor shower competes with August’s Perseids for showiness — yet it’s not nearly as well-known. The Geminids are easier on your sleep schedule, too. Their radiant (near Castor in Gemini) climbs as high by 11 p.m. standard time (45 degrees above the local horizon) as the Perseid radiant does by 2 a.m. daylight time on the peak Perseid nights. The higher the radiant, the more meteors you’ll see.

The Geminid meteors can flash into view anywhere in the late-night sky when the shower peaks in mid-December. But if you follow their paths back far enough, they all appear to diverge from a point in the constellation Gemini.

The International Meteor Organization (IMO) predicts that the Geminids should reach an impressive zenithal hourly rate of 120 this year. (ZHR is how many meteors you’d see see per hour in a very dark sky if the radiant were at the zenith. This year the peak should be centered on roughly 18h Universal Time on December 14. Unfortunately, that’s 1 p.m. EST and 10 a.m. PST. So in North America the shower’s performance is likely to be similar on the nights of December 13-14 and 14-15.

This week’s sky at a glance

As the IMO notes, “Near-peak Geminid rates persist for almost a day, so much of the world has a chance to enjoy something of the shower’s best.” In addition, “mass-sorting within the stream means fainter telescopic meteors should be most abundant almost a day ahead of the visual maximum,” and the meteors after maximum are typically brighter than average.

The moon will be a waxing crescent a few days old, no trouble at all.

Read More Here

Earth Approaching Objects : December 13th, 2015

……………………………………………………………..

NASA Confirms 60 feet Asteroid is on Course for a Close Encounter with Earth

nemesis maturity

……….

……….

Published on Dec 13, 2015

It’s hurtling through space at 35,000 miles per hour and this 60 feet space rock will have a very close encounter with earth

Asteroid 2015 XY261, which was first observed on December 12, 2015, will pass within 0.8 lunar distances (the distance between Earth and the Moon) of Earth.
The space rock is going to pass very close to our planet with a Condition code of 7 – MPC “U” parameter: orbit uncertainty estimate 0-9, with 0 being good, and 9 being highly uncertain.

There are currently 8 known NEO asteroids discovered that will pass with less than 10 LD’s up to the end of this month.
Two mountain-sized asteroids will safely pass on Dec, 24th and 29th.
http://lunarmeteoritehunters.blogspot…
http://ssd.jpl.nasa.gov/sbdb.cgi?sstr…
http://neo.jpl.nasa.gov/ca/
http://www.jpl.nasa.gov/asteroidwatch/

While confirming that the asteroid is not a threat to Earth, scientists say that if the asteroid were on course to impact earth it would cause a multimegaton atmospheric explosion over Earth’s surface, rather than impacting it. It potentially would be quite damaging (and even lethal) out to distances of 20 to 40 kilometers in all directions if it happened over a populated region with weak structures.

There is a roughly 50 percent chance of a 30-meter-plus asteroid striking Earth each century, according to NLSI team member Clark Chapman, space scientist at the Southwest Research Institute in Boulder, Colo.

Please report your meteor sightings to this website for posting- Remember IF you are looking for a report and no one reports then everyone lacks information; thank you.
http://lunarmeteoritehunters.blogspot…

Music credit: Impact Prelude by Kevin MacLeod is licensed under a Creative Commons Attribution licence (https://creativecommons.org/licenses/…)
Source: http://incompetech.com/music/royalty-…
Artist: http://incompetech.com/

…………………………………………………………………………….

All Sky Fireball Network

Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA’s Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth’s atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.

On Dec. 13, 2015, the network reported 29 fireballs.
(15 Geminids, 10 sporadics, 2 December Monocerotids, 1 Quadrantid, 1 alpha Canis Majorid)

In this diagram of the inner solar system, all of the fireball orbits intersect at a single point–Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]

Near Earth Asteroids

Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.

On December 13, 2015 there were potentially hazardous asteroids.

Recent & Upcoming Earth-asteroid encounters:

Asteroid	Date(UT)	Miss Distance	Size
2015 XU169	Dec 10	9.5 LD	16 m
1998 WT24	Dec 11	10.9 LD	1.1 km
2015 XA169	Dec 12	7.4 LD	15 m
2015 XR169	Dec 13	1.3 LD	8 m
2015 XX128	Dec 14	2.4 LD	25 m
2015 XX169	Dec 14	8.4 LD	14 m
2015 XN55	Dec 15	2.5 LD	15 m
2015 XY261	Dec 15	0.8 LD	16 m
2015 XL261	Dec 17	9.7 LD	42 m
2015 XE1	Dec 19	13.2 LD	29 m
2015 XN261	Dec 23	2.6 LD	31 m
2011 YD29	Dec 24	9.7 LD	24 m
2003 SD220	Dec 24	28.4 LD	1.8 km
2008 CM	Dec 29	22.8 LD	1.5 km
2004 MQ1	Jan 2	55.4 LD	1.1 km
1999 JV6	Jan 6	12.6 LD	410 m
1685 Toro	Jan 22	60.9 LD	1.7 km
2001 XR1	Jan 23	74.4 LD	1.5 km
2015 VC2	Jan 28	5.8 LD	15 m

Notes: LD means “Lunar Distance.” 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.

………………………………………………………………………………

Hubble Space Telescope has produced this beautiful image of the inner parts of the distant galaxy NGC 7252.

……………………………………………………………..

 

NGC 7252: Hubble Captures Image of Atoms for Peace Galaxy

Dec 7, 2015 by Sergio Prostak

The NASA/ESA Hubble Space Telescope has produced this beautiful image of the inner parts of the distant galaxy NGC 7252.

This image shows the central regions of the peculiar galaxy NGC 7252. Image credit: NASA / ESA / Hubble / Judy Schmidt, http://www.geckzilla.com.

NGC 7252, also known as LEDA 68612 or Arp 226, is a 12.7 magnitude peculiar galaxy in the constellation Aquarius.

It is about 212 million light-years distant and almost 200,000 light years across.

The galaxy has an odd nickname. In December 1953, President Eisenhower gave a speech that was dubbed Atoms for Peace.

The theme was promoting nuclear power for peaceful purposes – a particularly hot topic at the time.

This speech and the associated conference made waves in the scientific community and beyond to such an extent that NGC 7252 was named the Atoms for Peace galaxy.

This nickname is quite ironic, as the galaxy’s past was anything but peaceful.

Its peculiar appearance is the result of a collision between two similar gas-rich disc galaxies that took place about 600 million years ago, which ripped both galaxies apart.

The loop-like outer structures, likely made up of dust and stars flung outwards by the crash, but recalling orbiting electrons in an atom, are partly responsible for the galaxy’s nickname.

 

 

Read More Here

Exploding meteor spotted in the night sky over the Lower Mainland and Western Washington.

…………………………………………………………..

 

The Province

Exploding meteor: Bright bolide lights up Friday night sky from Chilliwack to Nanaimo to Seattle

By PATRICK JOHNSTON, The Province December 5, 2015

A bolide, or exploding meteor, similar to this one was spotted in the night sky over the Lower Mainland and Western Washington on Friday night.

Photograph by: NASA , The Province

 

Tina Robertson was just trying to catch a stray cat out in front of her property when she heard it.

“It freaked me right out,” she said.

Then she looked up to see a “big ball of fire.”

“It was moving like hell,” she said. “It was big, but not as big as that one in Russia.”

What she and other witnesses as far afield as Seattle and Nanaimo seem to have seen around 6:50 p.m. Friday was a type of meteor known as a bolide. Bolides are as bright as a full moon; they’re a meteor that doesn’t just burn up as it travels through the atmosphere, it explodes.

(Hat tip to Seattle Twitter user Reb Roush for pointing us all to the term.)

Robertson’s partner Wilf Krickhan was loading up firewood in a bobcat behind the house when he saw the blue-green bolide flash across the sky.

 

Read More Here

An international team of astrophysicists has for the first time witnessed a star being swallowed by a black hole and ejecting a flare of matter moving at nearly the speed of light.

…………………………………………………………

 

---

Your source for the latest research news

Scientists get first glimpse of black hole eating star, ejecting high-speed flare

Date:

November 27, 2015

Source:

Johns Hopkins University

Summary:

An international team of astrophysicists has for the first time witnessed a star being swallowed by a black hole and ejecting a flare of matter moving at nearly the speed of light.

---

This artists impression shows a black hole consuming a star that has been torn apart by the black hole’s strong gravity. As a result of this massive “meal” the black hole begins to launch a powerful jet that we can detect with radio telescopes.

Credit: NASA/Goddard Space Flight Center/Swift

An international team of astrophysicists led by a Johns Hopkins University scientist has for the first time witnessed a star being swallowed by a black hole and ejecting a flare of matter moving at nearly the speed of light.

The finding reported in the journal Science tracks the star — about the size of our sun — as it shifts from its customary path, slips into the gravitational pull of a supermassive black hole and is sucked in, said Sjoert van Velzen, a Hubble fellow at Johns Hopkins.

“These events are extremely rare,” van Velzen said. “It’s the first time we see everything from the stellar destruction followed by the launch of a conical outflow, also called a jet, and we watched it unfold over several months.”

Black holes are areas of space so dense that irresistible gravitational force stops the escape of matter, gas and even light, rendering them invisible and creating the effect of a void in the fabric of space. Astrophysicists had predicted that when a black hole is force-fed a large amount of gas, in this case a whole star, then a fast-moving jet of plasma — elementary particles in a magnetic field — can escape from near the black hole rim, or “event horizon.” This study suggests this prediction was correct, the scientists said.

“Previous efforts to find evidence for these jets, including my own, were late to the game,” said van Velzen, who led the analysis and coordinated the efforts of 13 other scientists in the United States, the Netherlands, Great Britain and Australia.

Supermassive black holes, the largest of black holes, are believed to exist at the center of most massive galaxies. This particular one lies at the lighter end of the supermassive black hole spectrum, at only about a million times the mass of our sun, but still packing the force to gobble a star.

The first observation of the star being destroyed was made by a team at the Ohio State University, using an optical telescope in Hawaii. That team announced its discovery on Twitter in early December 2014.

After reading about the event, van Velzen contacted an astrophysics team led by Rob Fender at the University of Oxford in Great Britain. That group used radio telescopes to follow up as fast as possible. They were just in time to catch the action.

By the time it was done, the international team had data from satellites and ground-based telescopes that gathered X-ray, radio and optical signals, providing a stunning “multi-wavelength” portrait of this event.

It helped that the galaxy in question is closer to Earth than those studied previously in hopes of tracking a jet emerging after the destruction of a star. This galaxy is about 300 million light years away, while the others were at least three times farther away. One light year is 5.88 trillion miles.

The first step for the international team was to rule out the possibility that the light was from a pre-existing expansive swirling mass called an “accretion disk” that forms when a black hole is sucking in matter from space. That helped to confirm that the sudden increase of light from the galaxy was due to a newly trapped star.

“The destruction of a star by a black hole is beautifully complicated, and far from understood,” van Velzen said. “From our observations, we learn the streams of stellar debris can organize and make a jet rather quickly, which is valuable input for constructing a complete theory of these events.”

Van Velzen last year completed his doctoral dissertation at Radboud University in the Netherlands, where he studied jets from supermassive black holes. In the last line of the dissertation, he expressed his hope to discover these events within four years. It turned out to take only a few months after the ceremony for his dissertation defense.

Van Velzen and his team were not the only ones to hunt for radio signals from this particular unlucky star. A group at Harvard observed the same source with radio telescopes in New Mexico and announced its results online. Both teams presented results at a workshop in Jerusalem in early November. It was the first time the two competing teams had met face to face.

“The meeting was an intense, yet very productive exchange of ideas about this source,” van Velzen said. “We still get along very well; I actually went for a long hike near the Dead Sea with the leader of the competing group.”

---

Story Source:

The above post is reprinted from materials provided by Johns Hopkins University. Note: Materials may be edited for content and length.

---

Journal Reference:

1. S. van Velzen, G. E. Anderson, N. C. Stone, M. Fraser, T. Wevers, B. D. Metzger, P. G. Jonker, A. J. van der Horst, T. D. Staley, A. J. Mendez, J. C. A. Miller-Jones, S. T. Hodgkin, H. C. Campbell, R. P. Fender. A radio jet from the optical and X-ray bright stellar tidal disruption flare ASASSN-14li. Science, 2015; DOI: 10.1126/science.aad1182

By studying data from NASA’s Spitzer Space Telescope, Astronomers conclude a mysterious dimming star was probably caused by a family of passing comets.

……………………………………………………….

 

 

Your source for the latest research news

Comet fragments best explanation of mysterious dimming star

Date:

November 25, 2015

Source:

Iowa State University

Summary:

Astronomers have responded to the buzz about a mysterious dimming star by studying data from NASA’s Spitzer Space Telescope. They conclude the dimming was probably caused by a family of comets passing in front of the star.

---

This illustration shows a star behind a shattered comet. Observations of the star KIC 8462852 by NASA’s Kepler and Spitzer space telescopes suggest that its unusual light signals are likely from dusty comet fragments, which blocked the light of the star as they passed in front of it in 2011 and 2013. The comets are thought to be traveling around the star in a very long, eccentric orbit.

Credit: Illustration by NASA/JPL-Caltech

Was it a catastrophic collision in the star’s asteroid belt? A giant impact that disrupted a nearby planet? A dusty cloud of rock and debris? A family of comets breaking apart? Or was it alien megastructures built to harvest the star’s energy?

Just what caused the mysterious dimming of star KIC 8462852?

Massimo Marengo, an Iowa State University associate professor of physics and astronomy, wondered when he saw all the buzz about the mysterious star found by citizen scientists on the Planet Hunters website.

Those citizen scientists were highlighting measurements of star brightness recorded by NASA’s Kepler spacecraft. Tiny dips in a star’s brightness can indicate a planet is passing in front of the star. That’s how Kepler astronomers — and citizen scientists using the internet to help analyze the light curves of stars — are looking for planets.

But this star had deep dips in brightness — up to 22 percent. The star’s brightness also changed irregularly, sometimes for days and even months at a time. A search of the 150,000-plus stars in Kepler’s database found nothing like this.

So Marengo and two other astronomers decided to take a close look at the star using data taken with the Infrared Array Camera of NASA’s Spitzer Space Telescope. They report their findings in a paper recently published online by The Astrophysical Journal Letters.

Their conclusion?

“The scenario in which the dimming in the KIC 8462852 light curve were caused by the destruction of a family of comets remains the preferred explanation …,” wrote the three — Marengo; Alan Hulsebus, an Iowa State doctoral student; and Sarah Willis, a former Iowa State graduate student now with the Massachusetts Institute of Technology’s Lincoln Laboratory.

Questions about the star were launched last month when a research team led by Tabetha Boyajian of Yale University reported on the star in the Monthly Notices of the Royal Astronomical Society. The astronomers reported how citizen scientists tagged the star’s deep and irregular dips in brightness as “bizarre” and “interesting.”

Boyajian and the other researchers looked at the data and investigated several possible causes. They wrote the “most promising theory” was a barrage of crumbling comets passing in front of the star.

In a subsequent paper submitted to The Astrophysical Journal, Jason Wright and colleagues at Penn State University speculated about other causes, including alien megastructures built to harvest energy while orbiting the star.

When the Iowa State astronomers studied the star with Spitzer infrared data from January 2015 — two years after the Kepler measurements — Marengo said they didn’t see much. If there had been some kind of catastrophe near the star, he said there would be a lot of dust and debris. And that would show up as extra infrared emissions.

Marengo said the study looked at two different infrared wavelengths: the shorter was consistent with a typical star and the longer showed some infrared emissions, but not enough to reach a detection threshold. The astronomers concluded there were no excess infrared emissions and therefore no sign of an asteroid belt collision, a giant impact on a planet or a dusty cloud of rock and debris.

So Marengo and his colleagues say the destruction of a family of comets near the star is the most likely explanation for the mysterious dimming. The comet fragments coming in rapidly at a steep, elliptical orbit could create a big debris cloud that could dim the star. Then the cloud would move off, restoring the star’s brightness and leaving no trace of excess infrared light.

And the alien megastructure theory?

“We didn’t look for that,” Marengo said. “We can’t really say it is, or is not. But what the star is doing is very strange. It’s interesting when you have phenomena like that — typically it means there’s some new physical explanation or a new concept to be discovered.”

---

Story Source:

The above post is reprinted from materials provided by Iowa State University. Note: Materials may be edited for content and length.

---

Journal Reference:

1. Massimo Marengo, Alan Hulsebus, Sarah Willis. KIC 8462852: THE INFRARED FLUX. The Astrophysical Journal, 2015; 814 (1): L15 DOI: 10.1088/2041-8205/814/1/L15

Images of Comet Catalina with her twin tails captured by amateur Astonomer , Chris Schur of Arizona.

………………………………………………………..

 

Phys.org

Comet Catalina grows two tails, soars at dawn

November 23, 2015 by Bob King, Universe Today

Comet C/2013 US10 Catalina shows off a compact green coma and two tails in this photo taken this morning (Nov. 22, 2015) at dawn from Arizona. The green color comes from carbon compounds fluorescing in UV sunlight. Credit: Chris Schur

Amateur astronomer Chris Schur of Arizona had only five minutes to observe and photograph Comet Catalina this morning before twilight got the better of the night. In that brief time, he secured two beautiful images and made a quick observation through his 80mm refractor. He writes:

“Very difficult observation on this one. (I observed) it visually with the 35mm Panoptic ocular. It was a round, slightly condensed object with no sign of the twin tails that show up in the images. After five minutes, we lost it visually as it was 2° degrees up in bright twilight. Images show it for a longer time and a beautiful emerald green head with two tails forming a Y shaped fan.”

North is up and east to the left in these two photos of the comet made by Dr. D.T. Durig at 6:23 a.m. EST on Nov. 21st from Cordell-Lorenz Observatory in Sewanee, Tenn. He estimated the coma diameter at ~2 arc minutes with a tail at least …

Read more at: http://phys.org/news/2015-11-comet-catalina-tails-soars-dawn.html#jCp

Schur estimated the comet’s brightness at around magnitude +6. What appears to be the dust tail extends to the lower right (southeast) with a narrower ion tail pointing north. With its twin tails, I’m reminded of a soaring eagle or perhaps a turkey vulture rocking back and forth on its wings. While they scavenge for food, Catalina soaks up sunlight.

I also headed out before dawn for a look. After a failed attempt to spot the new visitor on Saturday, I headed down to the Lake Superior shoreline at 5:30 a.m. today and waited until the comet rose above the murk. Using 7×50 binoculars in a similar narrow observing window, I could barely detect it as a small, fuzzy spot 2.5° south of 4th magnitude Lambda Virginis at 5:50 a.m. 10 minutes after the start of astronomical twilight. The camera did better!

 

Read More Here

Mars is destined to get a spectacular new planetary ring system to rival that of Saturn, in about 30 million years or so, according to scientists.

……………………………………………………….

 

ABC.net.au

Mars to get planetary ring set to rival Saturn, with moon Phobos set to break up from tidal stress

ABC Science

By Stuart Gary

Updated Mon at 2:50pm

Photo: A computer generated image of the rim of the red planet Mars. (NASA/JPL-Caltech)

Mars is destined to get a spectacular new planetary ring system to rival that of Saturn, but don’t hold your breath because it will not be for another 30 million years or so, according to scientists.

The findings, published in the journal Nature Geoscience, are based on a new study to determine the fate destined to befall the diminutive Martian moon Phobos.

Over time Phobos is creeping inwards towards Mars at a couple of centimetres per year.

Dr Benjamin Black

“We found that Phobos is too weak to withstand tidal stresses from Mars and we expect it to break apart in a few tens of millions of years and form a ring around Mars,” the study’s lead author Dr Benjamin Black of the University of California said.

Only the giant planets of the outer solar system have rings at the moment.

Phobos — the larger of the two moons circling Mars — orbits just 6,000 kilometres above the surface of the red planet, closer than any other moon in the solar system.

“Over time Phobos is creeping inwards towards Mars at a couple of centimetres per year,” Dr Black said.

“We wanted to figure out whether Phobos crashes into Mars or breaks apart to form a ring, so we needed to know how strong it was — is it going to be able to stand the increasing tidal stresses that are going to be pulling this little moon apart, or will it eventually succumb to these forces?”

Dr Black and co-author Tushar Mittal found that Phobos will be pulled apart by the red planet’s gravitational tidal forces in about 20 to 40 million years’ time.

“We concluded that Phobos would break apart between 2.4 and about 1.1 Mars radii, somewhere between 8,500 kilometres down to around 4,000 kilometres or so,” Dr Black said.

 

Read More Here