When they get close enough to a planet or moon, they will be pulled in by the large body's gravity and strike the surface at a speed of at least the escape velocity of the planet or moon, i.e., faster than a bullet.At such speeds, the projecticle explodes on impact and carves out a round bowl-shaped depression on the surface. How can you distinguish an impact crater from a volcanic crater?To be useful, radioisotopes with very short half-lives, such as those measured in seconds, hours, or days, are produced in nuclear reactors or cyclotrons close to the where they will be used. These radioisotopes are particularly useful in medical applications.
Average water level declines in the deeper aquifer system have been on the order of 0.46 m (1.5 ft) per year for the past 40-plus years.
Carbon-isotopic measurements on dissolved inorganic carbon were used to provide information on the relative ages of the ground water pumped from various locations within the basin.
Pripyat was once home to 50,000 people and is just a few miles from the Chernobyl power plant The footage shows Pripyat being taken over by nature.
Eerie views of rusted bumper cars and a Ferris wheel (pictured) are placed alongside golden flowers and trees growing among buildings.
The fourth reactor is pictured in 1982The Chernobyl disaster is the worst nuclear power plant accident in history in terms of cost and casualties, and is one of only two classified as a level 7 event on the International Nuclear Event Scale.
A Devon-based documentary maker recently captured the decaying region of Pripyat in Ukraine using a drone (pictured).
A longer half-life, such as hundreds or thousands of years, means that the radioisotope continues to emit harmful radiation for a very long period of time.
The table below gives the emitted radiation, half-life, and uses for a selection of useful isotopes in order of decreasing half-life.
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The spread of radiation following the 1986 explosion is pictured.