Science Ask Astro web extra: Why is the fourth known planet in an extrasolar system labeled with an “e”? Shouldn’t that be the fifth known planet? Or is the star always “a”?
Stars Is it true that there are more stars in the universe than there are grains of sand on Earth? How could one calculate such figures?
Science Ask Astro web extra: What would the Sun’s rays do to Earth if the ozone layer was no longer present?
