Hubble Space Telescope Current Affairs - 2019

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2006 VW139/288P: Astronomers spot strange binary asteroid with comet-like features

International team of astronomers using NASA’s Hubble Space Telescope have spotted an unusual object called 2006 VW139/288P having two asteroids orbiting each other with comet-like features. These include bright halo of material, called a coma, and long tail of dust. The odd object is first known binary asteroid that is also classified as a main-belt comet.

Asteroids and comets

Asteroids and comets are believed to be ancient remnants of earliest years of formation of our solar system more than four billion years ago. Asteroids are known as inactive, rocky body orbiting the Sun. Comets are bodies of ice, rock and organic compounds that can be several miles in diametre and they can be at times active. Ice of comets can vaporise in sunlight forming an atmosphere (coma) of dust and gas and, sometimes, a tail of dust and/or gas.

2006 VW139/288P

Hubble was used to image asteroid in September 2016 just before it made its closest approach to Sun. The images revealed that it was actually not one, but two asteroids of almost the same mass and size, orbiting each other at a distance of 96 km.

It was discovered by Spacewatch in November 2006 and its possible cometary activity was seen in November 2011 by Pan-STARRS after that it was given comet designation of 288P. The more recent Hubble observations revealed ongoing activity in binary system.

The combined features of binary asteroid are wide separation, near-equal component size, high eccentricity orbit, and comet-like activity. These make it unique among few known binary asteroids that have a wide separation.

Significance: Understanding of 2006 VW139/288P’s origin and evolution may provide new insights into early days of solar system. The main-belt comets may help to answer how water came to a bone-dry Earth billions of years ago. As it is different from all other known binary asteroids, it will also help to answer some questions about how common such systems are in the asteroid belt.

TRAPPIST-1 planets likely to have water

According to international team of astronomers, earth-sized planets orbiting ultracool TRAPPIST-1 dwarf star may have substantial amounts of water and could be habitable.

They had used Hubble Space Telescope (HST), a joint project of European Space Agency (ESA) and NASA to estimate whether there is water on seven planets orbiting in TRAPPIST-1 planetary system.

Key Facts

Astronomers had examined amount of ultraviolet radiation (UV) received by individual planets of system to detect presence of water. UV radiation is important factor in atmospheric evolution of planets as it can break water vapour in atmospheres of planets into hydrogen and oxygen in process called photodissociation.

UV rays with more energy and X-rays heat upper atmosphere of planet, which allows hydrogen and oxygen, products of photodissociation to escape. Hydrogen gas escaped from exoplanets’ atmospheres was dectected by HST indicating it as a possible indicator of atmospheric water vapour.

The results suggest that outer planets of TRAPPIST-1 planetary system may harbour substantial amounts of water. This includes three planets within habitable zone (Goldilocks zone) of star, lending further weight to the possibility that they may indeed be habitable and support alien life.

The observed amount of UV radiation emitted by TRAPPIST-1 suggests that planets could have lost gigantic amounts of water over course of their history. The inner planets (TRAPPIST-1b, 1c, 1d) could have lost water worth more than 20 Earth- oceans- during the last eight billion years. However, outer planets of system (e, f and g) which are in habitable zone might have lost much less water, suggesting that they could have retained some on their surfaces.


The seven Earth-sized planets (named TRAPPIST-1b, c, d, e, f, g and h) orbiting ultracool dwarf star TRAPPIST-1 were discovered by astronomers in February 2017. The TRAPPIST-1 planetary system is 40 light-years away from Earth. Its dwarf star Trappist-1 is at least 500 million years old and is marginally larger than Jupiter. It has temperature of 2550K and shines with a feeble light about 2,000 times fainter than Earth’s sun.