How It Works - UK (2020-02)

http://www.howitworksdaily.com HowIt Works 087

Lee Wong

n We see white when many light colours reach

our eyes at once. ‘Perfect white’ would mix all

colours. The Sun doesn’t produce completely

perfect white, as some elements it contains

absorb a little bit of colour. It would be ver y

difficult, but it’s theoretically possible to make

perfect-white artificial light. AE

Is there a

perfect white?

© NASA

Ryan Davis

n New exoplanets are being discovered

all the time, so the answer to this question

never stays the same for ver y long. The

Habitable Exoplanets Catalog currently

lists 55 promising candidates, sorted by

Earth Similarit y Index (ESI) – an indicator

of how hospitable the surface temperature

and other conditions would be for

Earth-t y pe life. Topping the list w ith an

ESI of 93 per cent is Teegarden b, which

orbits a red dwarf star just 12 light years

from Earth. A nother recently discovered

contender for the title is K2-18b – the first

Earth-like exoplanet know n to have water

vapour in its atmosphere. AM

Which

exoplanet is

most likely to

have life on it?

Artist’s impression of K2-18b, which appears

hospitable to life due to the presence of water

© ESA

Madonna Power

n There are several reasons for tiny

door ways in old buildings. People were

slightly smaller during the 15th to 16th centur y

and therefore didn’t need high door frames,

although the fashion did require them to be

w ide. Many doors may look small, but this is

due to the rising street levels. As new roads

were built on top of old tracks, the doors

literally sank into the ground. Large manor

houses often incorporated small door ways

as a form of protection, since any intruder

would be required to bend dow n in order to

get in, thereby allow ing the homeow ner to

attack first. JE

Why are

doorways so

tiny in very old

buildings?

The front door of a Tudor timber-framed house

appears much smaller than that of a modern home

© Getty