Geologists estimate that the earth is approximately 4 billion years old, and astronomers calculate that the universe may be as much as 15 billion years old.
Izazi zesayensi yokwakheka kwephasi zilinganisela bona iphasi lineemnyaka emabhiliyoni ama-4 likhona, begodu izazi zeenkwekwezi zilinganisela bona indawo yoke kungenzeka bona ibe mnyaka emabhiliyoni ayi-15 ikhona.