BBC Knowledge June 2017

Why is the Moon colourless?

Despite appearances, the Moon is not

entirely devoid of colour. Apollo astronauts

described its colour as ‘brownish’.

Careful study shows that the dark areas,

or ‘maria’, display hints of blue or brown

while the highland areas have faint traces

of yellow, pink and pale blue. These

differences are mainly due to varying

amounts of metals such as iron

or titanium in the surface minerals.

Unfortunately, the human eye isn’t sensitive

enough to pick out these slight differences

in colour from a distance. However, much

of the lunar surface contains minerals that

are naturally grey and these dominate

the colour we perceive from Earth. AGu

It’s one of the most famous stories in medical science: Scottish bacteriologist Alexander

Fleming comes into his lab in London one day in 1928, and finds that bacteria on a test

dish seem to have been wiped out by some mould that had landed in the dish. Fleming

discovers the mould is secreting a compound he calls penicillin – it’s the world’s first

antibiotic. Antibiotics have since saved countless people from deadly bacterial infections.

Yet Fleming himself was unconvinced the penicillin could be turned into an effective

treatment and lost interest in his discovery. Credit for turning a chance finding into one

of the greatest medical breakthroughs ever should go to the Australian pathologist

Howard Florey and the German-born biochemist Ernst Chain. During the late 1930s,

they purified and stabilised penicillin, and, in 1941, became the first to treat a patient.

Despite a brief improvement, the patient died, as there wasn’t enough of the wonder drug.

This led Florey to cajole the giant US pharmaceutical companies into setting up mass-

production facilities. By the D-Day landings of 1944, there was enough penicillin to treat

thousands of injured troops who would otherwise have died. The following year, Fleming

won the Nobel – along with Florey and Chain. RM

WHO REALLY DISCOVERED?

PENICILLIN

ALEXANDER FLEMING HOWARD FLOREY ERNST CHAIN

Can a computer generate

a truly random number?

Computers are often required to produce

random numbers as they’re useful for a host

of tasks, from taking random samples of data

to simulating the formation of galaxies.

But computers produce these numbers using

mathematical formulas, which means they

aren’t truly random. This isn’t as bad as

it seems, as true randomness is prone to

producing bizarre patterns that can fool

researchers into seeing effects that don’t exist.

To avoid this, the so-called pseudo-random

number generators (PRNGs) formulas used in

computers undergo statistical tests to keep

the risk of long ‘runs’ below a certain threshold.

Even so, some computer-generated random

numbers have still caused problems. Subtle

patterns in the output of the so-called RANDU

generator created by IBM in the 1960s

is suspected to have undermined the reliability

of many research projects over the years.RM

Panels that convert solar energy into electricity

last for decades, but, when they do eventually

wear out, they can be turned into new products

• including fresh solar panels. Most of
  the materials they’re made from, such as glass,
  aluminium and copper, has been recycled for
  years. The semiconductor materials in them,
  such as silicon and cadmium telluride,
  can virtually all be recovered
  by specialist companies.RM

CAN SOLAR PANELS

BE RECYCLED?

| & ANSWERS

QUESTIONS

18 June 2017