Scientists are studying a layer of sedimentary rock and discover what appears to be ripples made by running water preserved in the rock. When comparing those ripples to some made in mud at a present day location, they notice that the effects are identical. Based on the observations, which of the following is most likely to be true?

How many countries have portuguese as a national language?

Based on what you know about the location of the earth in relation to the sun, why is this called the goldilocks zone in other galaxies?

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.