BBC Knowledge Asia Edition

Why do beached whales often die?

Death is often due to dehydration.

Whales have an incredibly thick layer of

insulating blubber. Without the water to

keep them cool, they overheat and lose too

much water via evaporation from their lungs.

Whales can also drown as the tide comes in

because they are lying on their side and the

water covers their blowhole before it’s deep

enough for them to swim free. Even if they

do get back into the water, many whales die

a few hours later because their huge weight

causes crush injuries that release toxic

breakdown products into their blood when

the pressure is removed. LV

The light from the Sun follows an

‘inverse-square law’. So, if you’re twice as

far from the Sun as the Earth, for example,

you’ll receive one-quarter of the amount of

light. Four times further away and you’ll

receive one-sixteenth the amount.

The average distance of Pluto from the

Sun is about 39 times that of the Earth’s.

So, on average, the Sun on Pluto looks

about 1,520 times fainter than it does on

Earth. But this isn’t particularly faint. The

full Moon is on average about 400,000

times fainter than the Sun. So, doing the

maths, this means the Sun seen from

Pluto is about 264 times brighter than the

full Moon. This is about the amount of

light you’d see on Earth when the Sun is

around four degrees below the horizon,

during ‘civil twilight’, which is more than

enough to read by. Even on Pluto,

looking directly at the Sun would

probably be painful. AG

How bright is daylight on Pluto?

Pack your sunglasses

for a holiday to Pluto

PHOTO: ATSUHIRO MUTO, US ANTARCTIC PROGRAM, DANIEL LEUSSIER/WIKI, CHINARE, SAMSARA/WIKI, BECHER0804/WIKI, EUPHRO/FLICKR, MAARTEN TAKENS/FLICKR, NASA, ALAMY X2, PRESS ASSOCIATION, GETTY, SCIENCE PHOTO LIBRARY X2

1. Dome Fuji,
   Antarctica
   Temperature: -93.2°C
   When: August 2010
   2. Vostok Research
   Station, Antarctica
   Temperature: -89.2°C
   When: July 1983


2. Amundsen-Scott
   South Pole Station,
   Antarctica
   Temperature: -82.8°C
   When: June 1982


3. Dome Argus,
   Antarctic Plateau
   Temperature: -82.5°C
   When: July 2005


4. Mount McKinley,
   Alaska
   Temperature: -73.8°C
   When: sometime
   between 1950 and 1969


5. Verkhoyansk,
   Russia
   Temperature: -69.8°C
   When: February 1892


6. Klinck research
   station, Greenland
   Temperature: -69.4°C
   When: December 1991


7. Oymyakon, Russia
   Temperature: -67.8°C
   When: February 1933


8. North Ice,
   Greenland
   Temperature: -66.1°C
   When: January 1954


9. Snag, Yukon,
   Canada
   Temperature: -62.7°C
   When: February 1947

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