Assume that one grain of sand has an average size of 1 millimeter across. based on the chemical composition of sand, can you guess how many atoms are in just one grain of sand? twenty million? twenty billion? keep going. twenty trillion? twenty quadrillion? you're not there yet! twenty quintillion—or the number 2 followed by nineteen zeros—is an approximation of the number of atoms in one grain of sand. but how much is that?

Thermohaline circulation and gyres

1. why does the same side of the moon always face earthc.the rotational period of the moon is equal to one revolution around earth2. which is greater the moons period of rotation or its period of revolution  b.the moons revolution period around earth3.what was the major accomplishment of the apollo missions  c.sending the first human into space4. which of these space missions involved the deployment of lunar roversa. voyager 15. which scientists are going to explore next on kepler-186fd. evidence of existence of life6.which mission is not going to explore the outside of the solar  systemb.safir7.which technology limit the future of space explorationb. scientist must first develop certain technologies before missions can be completed.