Child FAQ

What is a greenhouse?

A greenhouse is a house made of glass. It has glass walls and a glass roof. People grow tomatoes and flowers and other plants in them. A greenhouse stays warm inside, even during winter. Sunlight shines in and warms the plants and air inside. But the heat is trapped by the glass and can't escape. So during the daylight hours, it gets warmer and warmer inside a greenhouse, and stays pretty warm at night too.

Will we ever discover aliens?

 No one knows how rare alien life is in the universe, so there's no telling whether humanity will ever manage to discover it. However, scientists at the SETI Institute in California, who are engaged in the search for extraterrestrial intelligence, are hopeful that they'll detect alien signals within the next 20 years.

The scientists scan the night sky looking for unnatural radio or light beams — ones that could only emanate from an intelligent civilization. Their 20-year estimate is based on the rapid pace with which astronomers are discovering planets beyond our solar system, including planets that seem suitable for life; it is also based on the assumption that, if there are intelligent beings out there, they, too, will seek contact with others, and will make their presence known by sending signals into space.

Why is the moon sometimes out during the day?

The moon is just as likely to be visible during the day as it is at night — it orbits Earth independently of the sun. When its orbit brings it to your part of the sky during daylight hours, it is illuminated by the sun, and we can see it.