Italian boundary clay iridium asteroid impact clue

A thin clay layer held unusual iridium

Up To 160× Background

A thin layer of clay in Italy contained up to 160 times the usual amount of iridium. Because iridium is rare on Earth but common in asteroids, researchers proposed that a vaporized impactor spread it around the planet before they identified the crater.

Earth's magnetic bubble is much longer on one side

~10 vs >200 Earth radii

On the side facing the Sun, Earth's magnetic region reaches about 10 Earth radii into space. On the other side, the solar wind stretches it into a long tail more than 200 Earth radii long. Earth's magnetic surroundings are therefore far from symmetrical.

Greek writing added letters for vowel sounds

The Phoenician writing system used letters for consonants, but not vowels. When the Greeks adapted it, they reused some letters for vowel sounds. Greek became the earliest alphabet in the strict sense: a writing system with letters for both vowels and consonants.

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Italian boundary clay iridium asteroid impact clue

A thin clay layer held unusual iridium

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