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Who invented the calendar? – Audrey, 9, Oregon

Dear Audrey,

I use a calendar to keep up with my work as a science cat. I also love calendar apps that count down to big events—like my birthday. People have always tracked time for work and holidays.

I talked about this with my friend Nikolaus Overtoom. He’s a professor of ancient history at Washington State University.

He told me we use the Gregorian calendar today. That's a revised version of the Julian calendar. The Romans invented the Julian calendar.

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What diseases spread on pirate ships? – Anika, 9, Georgia

Dear Anika,

A pirate’s life was dangerous. They attacked other ships and battled other pirates as well as the law. But they were also at the mercy of another foe: sickness.

I talked about this with my friend Lawrence Hatter. He’s a history professor at Washington State University.

He told me the big era for pirates was 1710 to 1730. It was a time when lots of sailors were out of work. Some of them became pirates.

Here are four kinds of disease they might face on the job: scurvy, mosquito-borne diseases, infectious diseases and gangrene.

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Dear Dr. Universe: How do people name continents or places on earth? Thank you. - Lila Grace, 8, Virginia

Our world is full of so many different places. They get their names in lots of different ways. One way a place might get a name is from the person who explored it. The Americas are named after an Italian explorer, Amerigo Vespucci. But Amerigo wasn’t the first person to explore these continents. There were already people living there when he arrived. Still, “America” was named after Amerigo. For the most part, people name things because they are claiming possession of a place. Because of that, sometimes the original names of places are lost or erased. That’s what I found out from my friend Theresa Jordan, a history professor who teaches a geography course at Washington State University. Read More ...