<span>So far, astronomers have found more than 500 solar systemsand are discovering new ones every year. Given how many they have found in our own neighborhood of the Milky Way galaxy, scientists estimate that there may be tens of billions of solar systems in our galaxy, perhaps even as many as 100 billion.</span>
Answer:
Fortified Settlements
Explanation:
A castle is a type of fortified structure built during the Middle Ages predominantly by the nobility or royalty and by military orders.
Cold air is correct answer
Answer:
Lunar eclipses
The only shape that casts a round shadow no matter which direction it is pointed is a sphere, and the ancient Greeks deduced that this must mean the Earth is spherical.
Explanation:
