What is a light-year?

The new discovery of chemicals in
the atmosphere of a planet orbiting
a red dwarf star, that may indicate
an abundance of aquatic life, is some
124 light years from Earth

K2-18b
Orbits cool red dwarf
star in constellation of
Leo. Scientists have
discovered two
chemicals in its
atmosphere that on
Earth are only known
to be produced by life –
dimethyl sulphide and
dimethyl disulphide

LIGHT-TIME: DISTANCE LIGHT TRAVELS
WITHIN SPECIFIC PERIOD OF TIME

SUN

One light-second: 300,000 km

One light-minute: 18 million km

RED LINE INDICATES PREVIOUS MEASURE

One light-hour: 1.1 billion km

EARTH (8 MINS) JUPITER (43 MINS)

One light-day: 25.9 billion km

SOLAR SYSTEM

One light-year: 9.5 trillion km

200 light-years: 1.9 quadrillion km

K2-18b (124 LIGHT-YEARS)

100,000 light-years: 946 quadrillion km

MILKY WAY GALAXY

Pictures: NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University), NASA/JPL-Caltech.
Sources: BBC, Guardian, New York Times, NASA
© GRAPHIC NEWS