Answer:
Zicrons
Explanation:
The oldest of the zircons in the study, which came from the Jack Hills of Western Australia, were around 4.3 billion years old—which means these nearly indestructible minerals formed when the Earth itself was in its infancy, only roughly 200 million years old.
Doldrum is the region of very calm and little or no wind on either side of the equator. Doldrums which is also called convergence zone is an equatorial region of the Atlantic ocean which has sudden storms and light unppredictable winds. In addition doldrum is abelt around the earth near the equator where the sailing ships sometimes get stuck on windless water.
Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
Answer:
Properties of Bar Graphs
Each bar or column in a bar graph is of equal width. All bars have a common base. The height of the bar corresponds to the value of the data. The distance between each bar is the same.
Over fishing can affect the seas