This state of affairs won’t last forever. The Moon started its existence much closer to Earth, and has been slowly drifting outward at the rate of about 1.5 inches (3.8 cm) per year. Once it makes it past 14,600 miles (23,500 km), it’ll appear too small from Earth to cover the Sun. But don’t panic if you haven’t seen an eclipse yet ― you’ve got another 600-million-plus years before that border is breached. In the meantime, you can get a preview during an annular eclipse, when the Sun, Moon and Earth align but the Moon’s orbit places it too far away from Earth to entirely block the disk of the Sun. During an annular eclipse, the sky takes on a twilight cast, but some of the Sun still shows.