What were the conditions of early earth?

Astudent observes a star from two positions of earth in its orbit, in summer and winter, and measures the change in the position of the star. which of these can be best calculated by this method?

Compare the composition of the moon's surface with the composition of the earth's surface.

Acertain species of fish can have either long or short fins. the allele for long fins is dominant over the allele for short fins. a heterozygous, long-finned fish is crossed with a homozygous, short-finned fish. of the offspring, will have long fins and be , and will have short fins and be .