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An extraordinary photograph of a double asteroid

publicado a la‎(s)‎ 3 jun. 2019 9:13 por Plataforma Sites Dgac   [ actualizado el 21 ago. 2020 12:23 ]
From Chile, the unique capabilities of the SPHERE instrument on ESO’s Very Large Telescope enabled it to obtain the sharpest images of the asteroid 1999 KW4 as it flew by Earth, reaching a minimum distance of 5.2 million kilometers on 25 May 2019.

The asteroid 1999 KW4
Earth’s most recent encounter with an asteroid took place on 15 February 2013, when a previously unknown asteroid 18 metres across exploded as it entered Earth's atmosphere over the Russian city of Chelyabinsk.

A few days ago, through the European Southern Observatory’s VLT (Very Large Telescope) located in Paranal, about 130 kilometers to the South of Antofagasta and 12 kilometers from Antofagasta’s shoreline, in Chile, it was obtained an extremely clear photograph of the asteroid that flew by at about 5.2 millions of kilometers from our planet.

According to scientists, the asteroid never presented a threat of collision with Earth. In facto, the researchers were able to predict its fly-by and prepare the observing campaign of the rocky mass that has a small natural satellite.

ESO’s astronomers took advantage of the opportunity to test actions to a possible dangerous NEO (Near Earth Object), proving that ESO’s state of the art technology could be critical in planetary defense.

The International Asteroid Warning Network (IAWN) coordinated a cross-organisational observing campaign of the asteroid 1999 KW4 as it flew by Earth, reaching a minimum distance of 5.2 million kilometers on 25 May 2019.

One kilometer wide

The asteroid, called 1999 KW4, is about 1.3 kilometers wide and does not pose any risk to Earth.

SPHERE, one of the very few instruments in the world capable of obtaining images sharp enough to distinguish the two components of the asteroid, is part of the VLT and has allowed to calculate that both rocks are separated by around 2,6 kilometers.

SPHERE was designed to observe exoplanets; its state-of-the-art adaptive optics (AO) system corrects for the turbulence of the atmosphere, delivering images as sharp as if the telescope were in space.

It is also equipped with coronagraphs to dim the glare of bright stars, exposing faint orbiting exoplanets.

70,000 kilometers per hour

SPHERE data helped astronomers characterise the double asteroid. In particular, it is now possible to measure whether the smaller satellite has the same composition as the larger object. 

“These data, combined with all those that are obtained on other telescopes through the IAWN campaign, will be essential for evaluating effective deflection strategies in the event that an asteroid was found to be on a collision course with Earth,” explained ESO astronomer Olivier Hainaut.

“In the worst possible case, this knowledge is also essential to predict how an asteroid could interact with the atmosphere and Earth’s surface, allowing us to mitigate damage in the event of a collision,” he added.

“The double asteroid was hurtling by the Earth at more than 70 000 km/h, making observing it with the VLT challenging,” said Diego Parraguez, who was piloting the telescope.

(Source: ESO)
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