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Why comets appear black? Indian-led scientists’ group finally finds answer

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Dr. Chaitanya Giri, Postdoctoral Research Scientist, Max Planck Institute for Solar System Research
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Bengaluru: A study by an international team from Europe and the US led by an Indian planetary scientist has resolved one of the mysteries that baffled astronomers.

Astronomical studies have shown that several small bodies – Centaurs and Trans-Neptunian Objects (TNOs) – in the outer solar system are having surfaces that are extremely dark but the origin of this color had remained unclear.

Centaurs estimated to number around 44,000 are minor planets with diameters larger than one kilometer. And TNOs are similar objects at a distance farther than Neptune, the most distant planet in the solar system.

Now, in a report published in the International Journal of Astrobiology, Dr. Chaitanya Giri, who led the research from the Max Planck Institute for Solar System Research in Germany, and co-workers claim to have found why these objects appear dark.

They say they have obtained experimental evidence that the darkness of these objects is due to presence on their surfaces of highly ‘carbonized’ organic material analogous to ‘Titan tholin’ — a substance first synthesized in the late 1970s in the laboratory of Carl Sagan and another Indian scientist Bishun Khare at Cornell University to simulate the atmosphere of Saturn’s moon ‘Titan’.

“We investigated the chemical structure and composition of ‘Titan tholin’ using multiple analytical techniques such as laser desorption, mass spectrometry, Raman spectroscopy, and field-emission scanning electron microscopy,” Giri told IANS in an email.

“The investigation led to the discovery of novel graphitic structural components within the larger macromolecular structure of Titan tholin,” he said.

“Like the dark appearance of coal, our research indicates that the graphite within the Titan tholin-like material on Centaurs and TNOs contributes to their extreme darkness.”

According to Giri, since Centaurs and TNOs are progenitors of comets, “the darkness of the comet’s surface can also be attributed to similar material.”

For instance comet “67P/Churyumov-Gerasimenko”, which was visited by Europe’s Rosetta space mission in 2014, “was extremely dark,” said Giri, who was a co-investigator on the mission.

Giri, who is currently with Japan’s Earth Life Science Institute at the Tokyo Institute of Technology, says the findings of this research will have far-reaching implications.

“For astronomers and planetary scientists, the prospect of complex organic material present on several objects in our Solar System is striking,” he said.

Astronomers might further use “Titan tholin” to study the surfaces of exoplanets (that are planets beyond our solar system) and planetary scientists could probe into the role of tholin-like material in shaping up organic-rich atmosphere and geology of several solar system objects.

“Chemists could further explore the exotic conformations in which ultra-complex organics exist in the universe and biologists would further probe whether such organics play any role in the origin of life on Earth,” he added.

Giri noted that in the past few years, interest in the small Solar System bodies had been on an ascent.

“Besides Europe’s Rosetta mission, NASA’s Dawn mission to dwarf planet Ceres and the New Horizons mission to dwarf planet Pluto all have given us glimpses to our yet unexplored and enormously diverse Solar System.”

Giri said the “Titan tholin” for his study was synthesized at the NASA Ames Research Center while chemical investigations were carried out at the Max Planck Institute for Solar System Research, NASA Goddard Space Flight Center, and at the Universities of Maryland (US), Nice (France), and Goettingen (Germany). (IANS)(Photo: chaitanyagiri.com)

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NASA’s Kepler Discovers Nearly 100 New Exoplanets

NASA researchers found that some of the signals were caused by multiple star systems or noise from the spacecraft

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UFO religion as a concept is now becoming a part of popular understanding.
Countless galaxies exist in the universe, each hiding secrets that humankind is yet to unearth. Pixabay
  • NASA’s Kepler has discovered nearly 100 new exoplanets
  • Some of the planets discovered are as large as Jupiter
  • NASA has also found planet which orbits very bright stars

An international team of scientists have confirmed the discovery of nearly 100 new exoplanets — planets located outside our solar system.

The discovery was based on data from the second mission of NASA’s Kepler Space Telescope or K2 released in 2014.

NASA has discovered nearly 100 exoplanets. Wikimedia Commons
NASA has discovered nearly 100 exoplanets. Wikimedia Commons

K2 searches for exoplanet transits by registering dips in light caused by the shadow of an exoplanet as it crosses in front of its host star.

NASA researchers found that some of the signals were caused by multiple star systems or noise from the spacecraft.

But they also detected planets that range from sub-Earth-sized to the size of Jupiter and larger.

Also Read: Milky Way’s neighbouring galaxy is of the same size, not bigger

One of the planets detected was orbiting a very bright star.

“We validated a planet on a 10-day orbit around a star called HD 212657, which is now the brightest star found by K2 missions to host a validated planet,” said lead author Andrew Mayo, a doctoral student at the National Space Institute (DTU Space) at the Technical University of Denmark.

Some of the planets found are as big as Jupiter. VOA
Some of the planets found are as big as Jupiter. VOA

For the study, appearing in the Astronomical Journal, the team started out analyzing 275 candidates of which 149 were validated as real exoplanets.

In turn 95 of these planets have proved to be new discoveries, Mayo said.

The Kepler spacecraft was first launched in 2009 to hunt for exoplanets in a single patch of sky, but in 2013 a mechanical failure crippled the telescope.

NASA has found many planets before as well. Wikimedia Commons
NASA has found many planets before as well. Wikimedia Commons

However, astronomers and engineers devised a way to repurpose and save the space telescope by changing its field of view periodically. This solution paved the way for the follow up K2 mission.

Adding the newly discovered exoplanets brings the total number of exoplanets by K2 mission to almost 300, the study said.

Also Read: NASA sounding rocket probing dark regions of space falter

The first planet orbiting a star similar to our own Sun was detected only in 1995. Today some 3,600 exoplanets have been found, ranging from rocky Earth-sized planets to large gas giants like Jupiter. IANS