How It Works - UK (2020-02)

http://www.howitworksdaily.com How It Works 073

DID YOU KNOW? Although four spacecraft have visited Saturn, only one – Cassini – has orbited the planet

Over1.4billionkilometresfromEarthononeof

Saturn’s 53 confirmedmoons,Titan,isa world

thatresemblesEarth...withsomesubstitutions.

Rock y outcrops are replaced with ic y mountains,

and rather than raging rivers of water, lakes of

methane have carved the surface. Much like our

planet has a c ycle of evaporation and

precipitation to form rain, Titan also experiences

cycles of rainfall, but it’s very different to Earth.

Liquid methane is evaporated around the

moon’s equator and falls as rain at the polar

regions. On Earth, hydrocarbons such as

methane act as a gas until placed in a

How liquid methane rains

down from Titan’s sky

Methane

showers

JUPITER’S

RED EYE

One of Jupiter’s most recognisable

features is the enormous red spot

marking the gas giant’s surface. Large

enough to engulf the Earth, this spot

is in fact a swirling storm, spinning at

speeds of at least 430 kilometres per

hour. It’s still unknown as to when the

scarlet storm started, but records show

that people have been observing Jupiter’s

Great Red Spot for around 400 years.

Image studies conducted on the spot

between 1979 and 2016 have shown

that the spot appears to be shrinking,

becoming rounder and taller and

intensifying in colour. It’s still relatively

unclear as to why Jupiter’s storm is

changing, although NASA’s Juno

spacecraft is currently orbiting the gas

giant collecting data in the hopes of

finding an explanation.

The first record of the Great Red Spot is a

drawing from 1831 by amateur

astronomer Samuel Heinrich Schwabe

© NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstad/Sean Doran © CC NC SA

pressurised tank. However, due to Titan’s

extremely cold temperatures – dropping to

around minus 179 degrees Celsius –

hydrocarbons act like a liquid, which follows a

similar c ycle we see on Earth. Without a strong

grav itational pull like the one we experience on

Earth, methane raindrops fall in slow motion.

Compared to the 9.2 metres per second that rain

falls on Earth, on Titan raindrops descend at a

speed of only 1.6 metres per second.

Due to its nitrogen-rich atmosphere, Titan’s

surface exhibits an organic brown hue

© NASA/JPL-Caltech/University of Arizona/University of Idaho

Artist’s impression of Titan’s

lake-covered surface

© Alamy

0

0.3

1.0

1.5

20

40

0

River

Volcanism? Organic sediments

Lake

HO/NH 23 Melt

I cts

HO/NH 23

Pume

CH 4 - N 2 clouds

CFog 26 H

Evaporation

AlthoughTitandoesn’treceiveas

muchheatfromtheSunasEarth

does,it stillreceivesenoughto

evaporatemethanefromitslakes.

Volcano

Methanestoredin thecrustis

heatedandsentintothe

atmosphereviavolcanicactivity.

Atmosphere

TheatmosphereonTitanis

mostlymadeofnitrogen.

EscapingTitan

Floatingascloudandhaze,methane

interactswithorganiccompoundsin

theatmosphere,releasinghydrogen

outintospacein theprocess.

Condensation

Evaporatedmethaneforms

cloudsin Titan’satmosphereuntil

it reachesaroundminus 185

degreesCelsiusandfallsasrain.

Methanelake

Inthenorthernregionsof

Titan,seasandlakesare

comprisedofliquidmethane.