FAQ

Where does space actually begin?
Space officially begins at the Kármán line, an internationally recognized boundary set at 100 kilometers (62 miles) above Earth's sea level. At this altitude, Earth's atmosphere becomes too thin for conventional aircraft to generate aerodynamic lift, requiring vehicles to reach orbital speed to stay aloft.
Is there sound in space?
No, space is a near-perfect vacuum, meaning sound waves have no medium—such as air or water—to travel through. While radio waves can propagate in space (which is how astronauts communicate), acoustic sound waves cannot deliver audible noise across the void.
How old is the universe, and how do scientists know?
The universe is approximately 13.8 billion years old. Astronomers determine this age by measuring the expansion rate of the universe (the Hubble constant) and analyzing the Cosmic Microwave Background (CMB) radiation—the faint thermal glow left over from the Big Bang.