What caused the Big Bang is still a mystery. And that's just one of the many unanswered questions, in spite of everything we do know about the birth of the Universe.
James, aged 8, of Sydney wants to know: are zombies real?
Taste dictates most food choices, but there's more to it than just the taste buds on your tongue.
Nicholas, aged 6, was watching TV one day when his tooth fell out. He noticed that the bottom edge of the tooth was very spiky. Now he wants to know why.
A seed contains nearly everything a tree needs to get growing. Just add a dash of water, a bit of warmth and the right location, and you'll be seeing green in no time.
Because of the way our brains work, we can remember songs and rhymes much more easily than just words or letters. The ABC song teaches kids the basics of the English language.
Sharks can't sneeze like we do, but they can do other cool tricks -- like making their stomach stick out of their mouth to get rid of unwanted stuff.
Bo, aged nine, wants to know why adults think video games are bad.
If a huge huntsman spider is sucked into a vacuum cleaner, can it crawl out later? Lucy, age eight, really, really needs to know.
Maëlle, 7, wants to know why some shells are smooth, while others are corrugated. It turns out that while corrugated shells are strong, smooth shells can move fast.
Plants on other planets are bound to be even weirder than the strangest ones we find on Earth – if they even exist.
Cats evolved in hot desert regions where there were lots of small animals to eat. So they evolved feet that are perfect for pouncing on prey, climbing, scratching and jumping from great heights.
People used to think that when they looked up at the night sky, they were seeing all of space. Then American astronomer Edwin Hubble found out something so amazing, NASA named a telescope after him.
Millie, aged 5, wants to know where money comes from. We asked an economist to explain.