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Last word

51¶¯Âş's popular Last Word series gives readers the opportunity to answer each other's questions about everyday science phenomena, from the shape of scones to the evolutionary history of toenails. To answer a question or ask a new one, email lastword@newscientist.com

2JAN5P2 Holland Street meets the steep Albion Hill in the Hanover neighbourhood of Brighton

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Do people in hilly towns have better health than those in flat towns?

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2CXYTWB Close up of a green cicada insect bug on a plant

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What triggers cicadas to make noises in unison, then go silent?

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purebred beagle puppy is learning the world in first time; Shutterstock ID 566398009; purchase_order: -; job: -; client: -; other: -

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Why do we say “aww†when we see small, fluffy things?

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K4E74X The Earth from space. This image elements furnished by NASA.

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If Earth stopped rotating, would this affect the force of gravity?

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Kudzu ( Pueraria lobata ) flowers. Fabbaceae perennial vine. Dark blue-purple fragrant butterfly-shaped flowers bloom in racemes from July to September. The roots are edible and medicinal.; Shutterstock ID 2360739029; purchase_order: -; job: -; client: -; other: -

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This week’s new questions

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2F4D4YW Two American crows sitting on a bare branch communicating with each other.

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This week’s new questions

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Yellow wash scrub sponge placed on wet blue background covered with drops of water in light room during household chores; Shutterstock ID 2167323189; purchase_order: -; job: -; client: -; other: -

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Why does a slightly damp sponge absorb water better than a dry one?

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In this Voyager 2 image of Saturn, obtained Aug. 11, 1981, from a range of 14.7 million kilometers (9.1 million miles), north is at the upper right edge of the disc. Seen above the planet are the satellites Dione (right) and Enceladus. This false-color print shows a green spot at the south edge of a yellow band; in true color, the spot would appear brown and the band white. A bright yellow spot slightly above and to the left in this image moves eastward relative to the green spot at a rate that allows it to pass the green feature in about 50 days. The convective clouds that appear between the two spots are typical of the region. Here, the smallest visible structures measure about 270 kilometers (170 miles). The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif. https://www.jpl.nasa.gov/images/pia01959-voyager-2-image-of-saturn

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What is the probability that Voyager 1 or 2 will hit a planet or star?

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FE11X8 Cyclist driving, at dusk, in a city street, with and without lights and safety clothing, bike safety, visibility at night

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Which bicycle lights are safest and give the best visibility?

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Asteroid impact event. Lateral sectioned view of an asteroid impact, similar to that which is thought to have caused the extinction of the dinosaurs around 65 million years ago. The impact took place at sea near the coast of the Yucatan Peninsula in Mexico, forming the Chicxulub crater (around 200 kilometres across). The impact threw trillions of tons of dust into the atmosphere and sent tsunamis (massive waves) around the globe, destroying coastal areas. Dust and water vapour in the atmosphere lowered global temperatures. Plant and then animal life began to die off. The dinosaurs never recovered, and mammals rose to become the dominant form of life.

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This week’s new questions

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2EXM9NK Hand Knuckle Finger Joint Crack. Fingers Snap

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How can popped knuckles be so exceptionally loud?

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2JP8KPY Very tight parking in Italy with a small dented family car bumper to bumper squashed in next to two cars in a parking bay with only inches to move.

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What is the shortest space a parked car can get out of? Part 2

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