With schools closing across the nation in response to coronavirus concerns, many students may be jumping for joy. Others are worried, scared or confused. But as the American essayist Ralph Waldo Emerson wrote, "Knowledge is the antidote to fear."

With that in mind, let's answer a few common questions about coronavirus.

Everybody keeps talking about "coronavirus" and "covid-19." Which is it?

Technically, either of these terms could be correct, depending on how they are used. The actual virus that appeared in China at the end of 2019 and has since hopped across the world is called "SARS-CoV-2," which is short for "Severe Acute Respiratory Syndrome" and "coronavirus." Once the virus gets into a person, it can cause an illness known as "Coronavirus Disease 2019," or covid-19. Also, you might hear it referred to as a "novel coronavirus," which means that scientists already knew about other coronaviruses, such as the one that caused an outbreak of SARS in Asia in 2003, but that this one is new.

How does covid-19 affect people?

The most common symptoms of covid-19 include fever, cough and/or shortness of breath. A person might develop one or more of these symptoms in as few as two days after being exposed to the virus, but they may also not feel sick for up to two weeks after contact.

Scientists say most people who get the virus will be able to fight it as they might a bad case of the flu; however, some people will have a harder time than others. Elderly people seem to be especially vulnerable, as are those with other conditions such as heart disease, lung disease or diabetes. Some people who have the virus won't even realize it, but in the worst cases, covid-19 can result in death. Fortunately, death is extremely unlikely to happen in infected children and teenagers.

Can pets get covid-19?

So far, one dog in Hong Kong has tested positive for the coronavirus. However, it isn't showing any symptoms, so it's unclear whether the virus can have a negative effect on pets. According to the World Health Organization, there is no evidence yet that dog owners can catch the virus from their pets. Of course, if you keep your animals inside and avoid walking them in public places, they will be even more unlikely to come into contact with the virus.

Why are schools, stores and restaurants closing?

Because SARS-CoV-2 is new, our immune systems haven't had a chance to learn how to fight it off. This allows the virus to move around quickly, infecting many new people for each group it comes into contact with. This makes schools, stores, restaurants and other public gatherings the perfect places for the virus to spread.

The biggest concern now, based on what's happened in countries such as Italy, is that if enough people get sick at the same time, hospitals might not be able to keep up with the demand for treatment. This is a problem for those who need treatment because of covid-19, but also for anyone else who might need medical services for everything from a twisted ankle or a cut requiring stitches to more serious conditions.

Can this coronavirus be stopped?

There are many scientists around the world working to develop a vaccine that could be used to halt the spread of this coronavirus for good. However, it will take time to develop that vaccine, and there are measures communities and families can adopt in the meantime to help slow the virus' spread.

Why do we have to wash our hands so often?

First, washing your hands after going to the restroom or before handling food is a great practice in general and can help you avoid catching all sorts of nasty illnesses. But hand-washing has become even more important as this coronavirus spreads. The easiest way to ensure you're washing your hands well enough is to use warm or cold water and soap and to keep scrubbing every inch of your fingers, thumbs, palms and wrists for the time it takes to sing "Happy Birthday to You" twice. The Centers for Disease Control and Prevention (CDC) has more tips at cdc.gov/handwashing. (Also, remember to cover your cough with a tissue or at least your inner elbow.)

What is "social distancing?"

If your parents no longer want you to play basketball with your neighbors or go to a party that was set for next weekend, it's probably on account of something called "social distancing." And while it seems like a bummer, experts say it's another way everyone can work together to limit the impact of this coronavirus.

The idea behind social distancing is simple. The fewer people we have close contact with each day, the fewer opportunities the virus has to spread. (The CDC says "close" is six feet or less.) And that means not only will you and your family have better chances of avoiding covid-19, but so will your grandparents, your Scout group and the person you sit next to in a bus - any of whom might be at a higher risk to have a more serious reaction from the virus.

How long will this last?

Unfortunately, no one can answer that question yet. The CDC recommends that large events be canceled or postponed for at least the next eight weeks. Your parents and teachers will be coming up with creative ways to pass the time.