Page 53 - All About Space 68 - 2017 UK

SPACE EXPLORATION
What can studying
the ice giants
tell us?

Jasper Grant
Although Uranus and Neptune are
both very different to Earth, learning
more about them can still help teach
ASTRONOMY astronomers about both our own
planet and exoplanets that we are
What is a star example, understanding how and
discovering around other stars. For
when Uranus and Neptune formed
fills in another piece of the jigsaw of
diagonal used for? were built, and how the formation
how the planets in the Solar System
of the other planets affected the
early Earth. SA

Olivia Andrews the light in a straight line, meaning down near the floor to look through
There are two main types of the focal point, which is where the the eyepiece.
telescopes: reflectors that use mirrors eyepiece is located, is at the opposite A star diagonal fixed to the eyepiece
to focus light, and refractors that use end of the telescope tube to the end prevents this by reflecting the
lenses. In a reflector, the light can be opening aperture. This is fine for when light by 90 degrees, so that the
reflected to a comfortable viewing looking at objects on the horizon, but eyepiece is now off to the side, like on
position, off to the side of the telescope for looking at objects near the zenith a reflecting telescope, which makes
tube, but the lenses in refractors focus (directly above) you would have to get refractors more comfortable to use. TM

SOLAR SYSTEM
How long ago was there water on Mars?

Mark Abbott
Liquid oceans Conditions for life Climate change Periodic flooding Subsurface rivers Ice and aquifers
4 BILLION YEARS AGO 3.8 BILLION YEARS AGO 3.5 BILLION YEARS AGO 2 BILLION YEARS AGO 1 BILLION YEARS AGO PRESENT DAY
During this volcanic The late heavy Mars cooled, and its During warm periods Despite harsh surface The surface of Mars is
period, the atmosphere bombardment ended, magnetic field dissipated. in the history of Mars, conditions, evidence of covered in permafrost,
was thicker, the planet and a liquid water ocean Up to 95 per cent of the subsurface ice melted fresh gullies is evident and there may still be
warmer, and the late may have covered the atmosphere was lost to which flooded the on crater slopes, possibly liquid water beneath
heavy bombardment northern hemisphere space, and air pressure planet, leaving chaotic caused by melted the surface, heated by
may have delivered of Mars, supplying rain dropped so low that channels into the subsurface ice dragging the residual warmth of
water-containing comets to the mountains in liquid water became Northern Lowlands. material on the surface the planet.
to the surface of Mars. the South. unstable on the surface. before it refreezes. © NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team, © ESO/B. Tafreshi, © NASA, © ESO, © ESO/B. Tafreshi, ©NASA/JPL-Caltech

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