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Indian-origin space scientist says India needs to focus on meteor defense

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Bengaluru: An Indian-origin space scientist said that India needs to focus on reconnaissance infrastructure, putting in place a meteor defence and develop a national meteor disaster preparedness policy after the last week Tamil Nadu incident in which a man was killed inside college campus by meteorite strike.

“Catastrophies originating from outer space are no fiction,” Chaitanya Giri, who was earlier with Max Planck Institute for Solar System Research in Germany and is currently with the Earth Life Science Institute in Tokyo, told this correspondent in an email.

Such catastrophies “are potential and credible threats to our national interests,” he said.

Giri said the US, in 2005, mandated its NASA space agency to build infrastructure for surveillance of potentially hazardous asteroids and to divert those on a likely collision course with Earth. The European Union, Japan, and Russia followed suit and are continually tracking comets and asteroids while Canada has its own “near earth object surveillance satellite” to identify unwelcome visitors from space, he said.

“Space capable India has not joined this club,” Giri said.

In fact, the seven-foot wide satellite junk that fell off the southern coast of Sri Lanka on November 13, 2015, was identified by a US ground-based sky survey infrastructure while its fall trajectory was projected by the the European Sky network, Giri said.

“While these nations have built up the networks to ward of dangers from space, India is totally unprepared to counter the impact of destructive meter-scale meteorites and extinction-level kilometre-scale asteroids or comets,” he said.

Giri said India’s prehistory is dotted with meteors of different sizes such as Lonar in Maharashtra (two km wide) and Ramgarh in Rajasthan (four km wide), adding an 11-km-wide meteorite that hit Dhala in Madhya Pradesh “could have unleashed energy many times higher than the largest atomic detonation”.

While it is true such kilometres-wide meteorites fall once in several thousand years, smaller metre-scale meteorites fall frequently and unleash limited regional destruction, he said.

Giri pointed out that a 20-year (1994-2013) global map released by NASA in 2014 shows numerous metre-scale meteors exploding all over the Indian Ocean region and the Indian sub-continent with energy approximately equivalent to the atomic bomb dropped over Nagasaki in 1945. Also, the Geological Survey of India (GSI) in the past 15 years has reported numerous meteoritic falls mostly centimetre-scale chunks from all over India.

In February 2013, a meteor, 20 metres in diameter, exploded 30 km above the city of Chelyabinsk in Russia with an energy approximately 25 times more powerful than the Nagasaki bomb, causing thousands of human injuries and damage worth billions of dollars. Bangkok experienced meteorite falls twice in September 2015. Nearer home, on February 27, 2015, a meteor exploded over Kozhikode, Malappuram, Palakkad and Thrissur in Kerala to finally impact at several locations in Ernakulam district. All these events demonstrate that the threat from meteors is real, Giri said.

With its massive geographical land mass and vast exclusive economic zone, India has all the legitimate reasons to develop a planetary defence programme of its own and create an operational national preparedness policy for various meteor disaster scenarios, he said.

“To this effect, New Delhi should exploit ISRO’s capabilities for constructing an indigenous ground- and space-based reconnaissance network that would track potentially hazardous objects as small as one metre,” he said. Had such a system been in place, there would have been no room for controversy over the cause of explosion heard in Vellore last week.

“The verdict whether it was due to meteorite or not should be supported by peer-reviewed evidence,” Giri said, dismissing news reports quoting scientists of the Indian Institute of Astrophysics (IIAP) in Bengaluru that the sample it examined did not look like meteorite.

“The Geological Survey of India is the authority on meteorite curation and not IIAP whose faculty are mainly astronomers,” Giri said. Further, the IIAP scientists did not collect the samples themselves but tested the sample given by the police “which is not the most appropriate thing to do,” he said.

“I also do not know if they looked for the presence of iridium, an element that you do not get on Earth and is predominantly extra-terrestrial in origin. Hence I do not consider IIAP’s sampling and verdict at face value.”

Giri said a video uploaded on the internet shows the trail of a meteor over Chennai with its trajectory towards the West (the direction to Vellore). If this video is true, the Vellore event is most likely due to meteorite, he said. (IANS)(image: mashable.com)

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Scientists: Milky Way Merged with Another Smaller Galaxy Roughly 10 Billion Years Ago

The Milky Way, home to our sun and billions of other stars, merged with another smaller galaxy in a colossal cosmic collision roughly 10 billion years ago

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Milky Way, Galaxy, Scientists
FILE - A view of the Milky Way from an area of Puyehue National Park near Osorno City, Chile, May 8, 2008. VOA

The Milky Way, home to our sun and billions of other stars, merged with another smaller galaxy in a colossal cosmic collision roughly 10 billion years ago, scientists said Monday, based on data from the Gaia space observatory.

The union of the Milky Way and the so-called dwarf galaxy Gaia-Enceladus increased our galaxy’s mass by about a quarter and triggered a period of accelerated star formation lasting about 2 to 4 billion years, the scientists said.

“Yes, indeed it was a pivotal moment,” said astronomer Carme Gallart of Instituto de Astrofisica de Canarias in Spain, lead author of the research published in the journal Nature Astronomy.

Galaxies of all types including the Milky Way began to form relatively soon after the Big Bang explosion that marked the beginning of the universe some 13.8 billion years ago, but were generally smaller than those seen today and were forming stars at a rapid rate. Subsequent galactic mergers were instrumental in configuring galaxies existing now.

Milky Way, Galaxy, Scientists
The merger of the Milky Way and the dwarf galaxy Gaia-Enceladus roughly 10 billion years ago, left, and the current appearance of the Milky Way galaxy, right, are shown in this artist’s conception, July 22, 2019. VOA

High-precision measurements of the position, brightness and distance of around a million stars within 6,500 light years of the sun, obtained by the Gaia space telescope operated by the European Space Agency, helped pinpoint stars present before the merger and those that formed afterward.

Certain stars with higher content of elements other than hydrogen or helium arose in the Milky Way, they found, and others with lower such content originated in Gaia-Enceladus, owing to its smaller mass.

While the merger was dramatic and helped shape what the Milky Way has become, it was not a star-destroying calamity.

“This crash was big in cosmic terms, but if it was happening now, we could probably not even notice at a human or solar system level,” Gallart said.

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“The distances between stars in a galaxy are so huge — a galaxy is basically empty space — that the two galaxies intermix, change their global shape, more star formation may happen in one, and maybe the small one stops forming stars.

“But the individual stars in each galaxy don’t collide, don’t really notice the force of the event in a way that affects their individual evolution or the evolution of the planetary systems that may be attached to them,” Gallart said.

The Milky Way, spiral shaped with a central bar-like structure composed of stars, includes 100 to 400 billion stars, including the sun, which formed roughly 4.5 billion years ago, far after the merger. (VOA)