Science — Page 5

The Eiffel Tower can be fifteen centimeters taller during the summer.

This phenomenon is due to the thermal expansion of iron. When the temperature rises, the metal molecules agitate and…

Diamonds can burn if heated to a high enough temperature.

Since diamonds are made of pure carbon, they can combust in the presence of oxygen if the temperature reaches about…

The metal gallium melts in the palm of a human hand.

The melting point of gallium is about thirty degrees Celsius. Since the human body temperature is around thirty-seven…

Osmium is the densest natural element: a litre of it would weigh more than 22 kilograms.

At about 22.6 grams per cubic centimetre, it is twice as dense as lead and slightly denser than iridium. It is a…

A corn kernel pops at about 180 °C, when the water inside it turns into steam.

The hard hull keeps the steam trapped, and the pressure rises to about nine times that of the air. When the hull…

On a very hot pan, water drops skate around and last longer than on a pan that is merely hot.

This is the Leidenfrost effect, described in 1756. Above about 200 °C, the underside of the drop evaporates instantly…

Fluorine is the most reactive chemical element and reacts even with glass and some noble gases.

It is so aggressive that several chemists were injured or killed trying to isolate it. The Frenchman Henri Moissan…

Aluminium was once more valuable than gold, and the tip of the Washington Monument is an aluminium pyramid.

Although it is the most abundant metal in Earth's crust, it was extremely hard to extract from ores. In 1884 the…

Penicillin was discovered by accident in 1928, in a mould that grew on a forgotten laboratory dish.

Returning from holiday, Alexander Fleming noticed that bacteria had died around a mould of the genus Penicillium…

The first X-ray image, made by Wilhelm Röntgen in 1895, showed his wife's hand, wedding ring and all.

Röntgen discovered an invisible type of radiation that passed through skin but was stopped by bones and metal. He…

For geologists, ice is a mineral, and a glacier is technically a rock.

A mineral is a natural, inorganic solid with a crystal structure and a defined chemical composition, and ice meets…

'Photo 51', taken in Rosalind Franklin's laboratory, was crucial to discovering the structure of DNA.

The image, made with X-rays in 1952 by the student Raymond Gosling under Franklin's supervision, showed an X-shaped…

Copper surfaces kill bacteria and viruses within a few hours.

Copper ions damage the membranes and genetic material of microbes. In 2020 a study showed that the new coronavirus…

Helium was discovered in the Sun in 1868, almost 30 years before it was found on Earth.

During an eclipse, astronomers saw a yellow line in sunlight that no known element could explain. Norman Lockyer…