Page 51 - All About Space 68 - 2017 UK
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SOLAR SYSTEM The Moon would have to
be 95 per cent closer to
How close would Earth to feel this effect
the Moon need to
get to Earth until it
was pulled apart?
Michael Woods
If the Moon was in an orbit getting
closer to Earth, it could reach a
distance of roughly 19,000 kilometres
(11,800 miles) before the gravity
of Earth began pulling its lunar
companion apart – this distance is
known as the ‘Roche limit’. Currently
the Moon sits at an average distance
of 384,400 kilometres (238,855 miles)
from us and is slowly moving away, so
there are absolutely no concerns for ASTRONOMY
this happening!
In this scenario, if the Moon got What’s the
closer to our planet, it would become furthest star I
deformed as Earth's tidal forces
overcame our lunar companion's can see with the
gravity. Material would then be naked eye?
stripped off the surface, which would
then fall towards us. LC Graham Hart
Which star is the most distant
is not exactly known, because
New Horizons has already taught of uncertainties in the distance
us much about the distant reaches measurements to those stars.
of our Solar System Although the Gaia spacecraft, which
is measuring the distances to a
billion stars, should provide greater
accuracy. One candidate is the
supergiant binary star Eta Carinae,
which is 7,500 light years away and
currently glows at magnitude 4.
Although in 1843 it briefly became
the second brightest star in the
sky, after experiencing an outburst.
Meanwhile, the red supergiant
star AH Scorpii is calculated to be
7,400 light years away, alternating
between magnitudes 6.5 and 9.6.
Of course, supernovae can shine
brighter than any normal star.
In 1987 a supernova exploded
in the Large Magellanic Cloud
168,000 light years away, reaching
magnitude 3, while a gamma-ray
SPACE EXPLORATION burst in 2008 briefly hit magnitude
5.3 from a distance of 7.5 billion
What will New Horizons do at its next target? light years! JB
Michael Woods known as 2014 MU69. New Horizons the formation of the planets. 2014
The New Horizons spacecraft is most will encounter the icy object on New MU69 is quite small, estimated to
famous for visiting Pluto in 2015, Year’s Day 2019, meeting it at its orbit be between 30-45 kilometres (20-30
but its mission is not yet over. It’s 6.5 billion kilometres (4 billion miles) miles) across and New Horizons will
heading deeper into the Kuiper Belt away from the Sun. The flyby will help photograph its surface, find out what
– which is the larger, icier equivalent teach scientists more about Kuiper Belt it’s made of, look for evidence of water
of the Asteroid Belt in the outer Solar objects in general, which are believed activity, and determine how similar it
System – towards a distant icy body to be leftover chunks of debris from is to Pluto, as well as comets. JB
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