The natural brightness of the night sky

A recent study analyzes data collected at 44 of the darkest places in the world, including the Canary Island Observatories, to develop the first complete reference method to measure the natural brightness of the night sky ...

Biologists discover a trigger for cell extrusion

For all animals, eliminating some cells is a necessary part of embryonic development. Living cells are also naturally sloughed off in mature tissues; for example, the lining of the intestine turns over every few days.

Parker discovers natural radio emission in Venus' atmosphere

During a brief swing by Venus, NASA's Parker Solar Probe detected a natural radio signal that revealed the spacecraft had flown through the planet's upper atmosphere. This was the first direct measurement of the Venusian ...

New model can predict carbon cycle presence on exoplanets

Life thrives at stable temperatures. On Earth, this is facilitated by the carbon cycle. Scientists at SRON, VU and RUG have now developed a model that predicts whether there is a carbon cycle present on exoplanets, provided ...

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Cycling

Cycling, also called bicycling or biking, is the use of bicycles for transport, recreation, or for sport. Persons engaged in cycling are cyclists or bicyclists. Apart from ordinary two-wheeled bicycles, cycling also includes riding unicycles, tricycles, quadracycles, and other similar human-powered vehicles (HPVs).

Bicycles were introduced in the 19th century and now number about one billion worldwide. They are the principal means of transportation in many regions.

Cycling is a very efficient and effective mode of transportation optimal for short to moderate distances. Bicycles provide numerous benefits compared to motor vehicles, including exercise, an alternative to the use of fossil fuels, no air or noise pollution, much reduced traffic congestion, easier parking, greater maneuverability, and access to both roads and paths. The advantages are at less financial cost to the user as well as society (negligible damage to roads, and less pavement required). Criticisms and disadvantages of cycling include reduced protection in crashes, particularly with motor vehicles, longer travel time (except in densely populated areas), vulnerability to weather conditions, difficulty in transporting passengers, and the skill and fitness required.

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