204K views · 2.5K reactions | Do you know why a total solar eclipse is so unique and so rare? During this rare event the Moon positions itself precisely between our planet and the Sun, creating a momentary blackout, revealing the Sun’s corona. It is a once-in-a-lifetime opportunity for most people as it casts a shadow on only a fraction of the Earth's surface. #Space #Science #Eclipse #SolarEclipse | Museum of Science, Boston | Facebook