On the lateral surface of the human brain, the central sulcus separates the frontal lobe from the parietal lobe. The lateral sulcus separates the frontal lobe from the temporal lobe. The frontal lobe bottom can be divided into a lateral, polar, orbital (above the orbit; also called basal or ventral), and medial part.
The age of an individual star can vary; they were all made at different times and have different life spans. Stars can range from a few million to a several billion years old. The oldest star yet discovered, HE 1523-0901, is an estimated 13.2 billion years old.
Main-Sequence Lifespan. The main sequence is the stage where a star spends most of its existence. Relative to other stages in a star's life it is extremely long; our Sun took about 20 million years to form but will spend about 10 billion years (1 Ã 10 10 years) as a main sequence star before evolving into a red giant.