All About Space - UK (2020-02)

Climate change

and the Huygens lander that touched down on the
satellite in 2005. “What it found shocked a lot of
us – it blew people’s minds,” says Way. Like Earth
there is liquid on the surface, which evaporates
and condenses as rain. Yet instead of water it is
methane, possibly because of the moon’s very
cold temperature. Researchers have also spotted
complex chemicals known to be the building blocks
of life. Understanding Titan’s climate today could
tell us whether it has ever had suitable conditions in
the past for this chemistry to jump from prebiotic
chains of molecules to full-blown biological
organisms. Dragonf ly could be a potential game
changer in this effort. In the summer of 2019, NASA
announced that it had approved the audacious
rotorcraft lander that would take off and land in
several sites across the Saturnian satellite, much
like its insect namesake. It is due for launch in 2026
and will arrive in 2034. According to Way, climate
modellers are “eagerly awaiting its arrival”.
All these efforts to understand the climates of
the worlds we share the Solar System with will
do more than just inform our own battle against
climate change. They will also give us a better idea
of what exactly makes a planet habitable in the long
term. That is sorely needed in the search for life
beyond the Solar System. If Venus was a pleasant
planet before volcanism ran rampant, then perhaps
we shouldn’t rule out planets in similar positions
to Venus around other stars. Maybe there is too
much focus on the idea of a habitable zone – the
narrow region around a star where the temperature
is right for liquid water. The contents of a planet’s
atmosphere has a huge role to play in distributing
heat, and surely needs to be taken into account
when assessing a world’s suitability for life. Who
knows, one day we may have to evacuate this
planet. If so, knowing which worlds around the Sun
and beyond could be new potential homes could
prove vital to the continuation of our species.

Above: Like

Earth, Mars

has been

through a

series of

ice ages

throughout

its history

Earth

What causes

climate chan

The sun

© Getty; Tobias Roetsch

© NASA/JPL

20km

50km

85km

690km

10,000km Theexosphere

Thislayer– upto

100,000kilometres

(62,140miles)from

theground– receives

sunlightfirst.

Theionosphere

Ourionosphere

shrinksandgrows

undertheinfluence

ofsolaractivity.

The

thermosphere

Thisisthelayerofour

atmosphereinwhich

auroralactivityoccurs.

The

mesosphere

Meteors– or

‘shootingstars’– are

seenwhenspace

dustburnsuphere. The

stratosphere

Ending 50 kilometres

(31miles)above

Earth,thisholdsthe

ozonelayer.

Thetroposphere

ThenearestlayertoEarth’s

surface,almostallweather

occurshere.

TheSun’score

Solarenergyismade

byfusinghydrogen

intohelium.

Theradiationzone

Sunlighttakesanaverageof

170,000yearstomakeitto

thetopofthislayer.

Theconvectionzone

Solarenergytakesjustthree

monthstoreachthetopof

thislayer.