As one of the most impressive astronomical events we can witness from Earth, a total solar eclipse is a jaw-dropping reminder that our planet is part of an elaborate celestial dance. However, due to the Moon’s orbit around the Earth and the Earth’s orbit around the Sun not being perfectly level with one another, this alignment is only precise every 18 months or so. Additionally, the Moon is moving away from us at a rate of about 3.8 centimeters per year, due to gravitational interactions between the Earth and the Moon. This means that eventually the Moon will appear too small in the sky to completely block the Sun’s surface, and total solar eclipses will cease. According to some back-of-the-envelope math, this will happen when the Moon’s orbit is about 23,000 kilometers wider than it is now, which will take around 600 million years. However, due to plate tectonics, climate events, and the movement of rock inside the Earth’s core and mantle, total solar eclipses will become much more irregular and infrequent around 620 million years from now, with the very last happening in around 1.2 billion years. Although this is a long time away, it is still a fleeting moment compared to how long our species has been around. Eventually, the Sun will become so bright that the Earth’s surface will be too hot for any life to thrive there, and so while total solar eclipses are numbered, so are ours.