A total lunar eclipse will make the moon appear red across the Western Hemisphere during the "Blood Worm Moon" this week.

When sunlight hits Earth’s atmosphere during a lunar eclipse, light frequencies toward the blue end of the visible spectrum are scattered outward, away from Earth’s umbra, but those with longer wavelengths, toward the red part of the spectrum, are bent inward and cast onto the moon.

Earth’s shadow will block most of the light that illuminates the lunar surface, creating what is known as a blood moon.