Astronomers have developed several ways to measure the vast distances between Earth and the stars and galaxies. What do you know about two of these techniques? A. An astronomical unit is about 93 million kilometers.

B. The A. U. is used to measure distance within our solar system.

C. A light-year (ly) is the distance that light can travel in one year in a vacuum.

D. An astronomical unit (A. U.) is the average distance between the Earth and the Sun.

E. Astronomers measure distances to objects which are outside our solar system in light-years.

in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.

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