Are an especially good indicator of climate change because scientists can find clues about ancient organisms and their environments. a. trace fossils b. trilobite fossils c. mineral replacements d. plant fossils

Why might have people followed the rivers to find their way into asia

What is the mercury length of time for one revolution around the sun?

One of the brightest comets of the 20th century was comet hyakutake, which passed close to the sun in early 1996. the orbital period of this comet is estimated to be about 30,000 years. find the semi-major axis of this comet’s orbit. compare it to the average sun-pluto distance and to the distance to alpha centauri, the nearest star to the sun, which is 4.3 light-years distant.