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Time-warp: Why June 30 will be a bit longer

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Washington: Strictly speaking, a day lasts 86,400 seconds. On June 30, the day will officially be a bit longer than usual because an extra second or “leap” second will be added and NASA has an explanation for this.

“The Earth’s rotation is gradually slowing down a bit, so leap seconds are a way to account for that,” said Daniel MacMillan, NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

This is the case according to the time standard that people use in their daily lives – Coordinated Universal Time or UTC.

UTC is “atomic time” — the duration of one second is based on extremely predictable electromagnetic transitions in atoms of cesium.

These transitions are so reliable that the cesium clock is accurate to one second in 1,400,000 years.

However, the mean solar day — the average length of a day, based on how long it takes the Earth to rotate — is about 86,400.002 seconds long.

“That is because the Earth’s rotation is gradually slowing down a bit owing to a kind of braking force caused by the gravitational tug of war between the Earth, the Moon and the Sun,” the US space agency said in a statement.

Scientists estimate that the mean solar day has not been 86,400 seconds long since the year 1820 or so.

This difference of two milliseconds, or two thousandths of a second — far less than the blink of an eye — hardly seems noticeable at first.

But if this small discrepancy were repeated every day for an entire year, it would add up to almost a second.

Typically, a leap second is inserted either on June 30 or December 31.

Normally, the clock would move from 23:59:59 to 00:00:00 the next day. But with the leap second on June 30, UTC will move from 23:59:59 to 23:59:60, and then to 00:00:00 on July 1.

In practice, many systems are instead turned off for one second.

Previous leap seconds have created challenges for some computer systems and generated some calls to abandon them altogether.

“In the short term, leap seconds are not as predictable as everyone would like,” said Chopo Ma, geophysicist at Goddard.

“The modelling of the Earth predicts that more and more leap seconds will be called for in the long-term but we cannot say that one will be needed every year,” Ma said.

From 1972, when leap seconds were first implemented, through 1999, leap seconds were added at a rate averaging close to one per year.

Since then, leap seconds have become less frequent.

This June’s leap second will be only the fourth to be added since 2000.

(IANS)

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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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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