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Roundup
The vast majority, 95%, are smaller than our Neptune,
which is four times the size of the Earth.
Four of the new planets are less than 2.5 times the size
of Earth, and they orbit their host suns in the “habitable
zone” - the region around a star where water can keep a
liquid state.
Whether that is the case on these planets cannot be
known for sure - Kepler’s target are hundreds of lightyears in the distance. This is too far away for very detailed
investigation.
Kepler was launched in 2009 on a $600m (£395m)
mission to assess the likely population of Earth-sized
planets in our Milky Way Galaxy.
Faulty pointing mechanisms eventually blunted its abilities
last year, but not before it had identified thousands of
possible, or candidate, worlds in a small patch of sky in
the Constellation Lyra.
It did this by detecting the periodic variations in the
brightness of stars caused by orbiting exoplanets passing
in front of them.
Douglas Hudgins from Nasa’s astrophysics division
summed up the significance of the latest news: “This is
the largest windfall of planets that’s ever been announced
at one time. Second, these results establish that planetary
systems with multiple planets around one star, like our
own Solar System, are in fact common.

Water spouts taller than Mt Everest appear to burst out of Europa when
it is farthest from Jupiter

Images by the Hubble Space Telescope show surpluses of
hydrogen and oxygen in the moon’s southern hemisphere,
say astronomers writing in Science journal.
If confirmed as water plumes, it raises hopes that
Europa’s underground ocean can be accessed from its
surface.
Future missions could probe these seas for signs of life.
Astrobiologists have said that, in theory, organisms could
survive in the oceans of Europa, but feared the moon’s
thick icy crust may be an impenetrable barrier to life.
Tidal forces. In this new study, US physicists looked at
images taken by Hubble in November and December of
last year, as well as older images from 1999.
In two distinct southern regions,
they saw evidence of water being
broken apart into hydrogen and
oxygen - revealed by ultraviolet
light signatures.

“Third, we know that small planets - planets ranging from
the size of Neptune down to the size of the Earth - make
up the majority of planets in our galaxy.”
One analysis of Kepler data published in November
suggested that perhaps one in five stars like our Sun hosts
an Earth-sized world located in the habitable zone.

Signatures of water (blue)
detected by Hubble are
overlayed on an image of
Europa

“They are consistent with two
200km-high (125-mile-high)
plumes of water vapour,” said
lead author Lorenz Roth, of
Southwest Research Institute,
San Antonio, Texas.
These giant geysers appear to
be transient - they arise for just
seven hours at a time.

They peak when Europa is at its farthest from Jupiter (the
apocentre of its orbit) and vanish when it comes closest
(the pericentre).
The habitable zone is the region around a star where water
can keep a liquid state.
Source: BBC News

Jupiter’s icy moon Europa ‘spouts water’
Water may be spouting from Jupiter’s icy moon Europa considered one of the best places to find alien life in the
Solar System.

This means that tidal acceleration could be driving water
spouting - by opening cracks in the surface ice, the
researchers propose.
They say the vapour jets may be like those seen on
Saturn’s moon Enceladus - with high-pressure emissions
escaping from very narrow cracks.
The results were reported at the American Geophysical
Union (AGU) Fall Meeting in San Francisco, California.
Source: BBC News
Africa Water, Sanitation & Hygiene • March - April 2014

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