Blood moons only occur during total lunar eclipses, when the Earth blocks the sun, but its atmosphere lets redder parts of sunlight through to reflect off the lunar surface.

Some maps may incorrectly identify the boundaries of a solar eclipse's totality because they assume the Earth is a smooth surface.

Because the half of Earth that faces the sun is larger than the area of the shadow cast by the moon during a solar eclipse, observers may experience a total, annular, or partial eclipse.

Although the moon passes between the sun and Earth each month, its orbit is tilted by five degrees, preventing Earth from experiencing a solar eclipse each month.

Solar eclipses are a cosmic coincidence because the moon is 400 times smaller than the sun but about 400 times closer to Earth, allowing it to block sunlight for those on Earth within its shadow.

Every eclipse is preceded or followed by another eclipse, separated by about two weeks and alternating between solar and lunar types.

Over thousands of years, the frequency of solar eclipses is greatest around the Arctic and Antarctic Circles and lowest near the equator.

The moon is slowly contracting as its interior cools, creating moonquakes and lobate scarps—cliffs that are steep on one side and gently sloping on the other—as the moon's surface buckles.

See a lunar eclipse share the night sky with the Milky Way

Photos taken at the Cerro Tololo Inter-American Observatory in Chile in March 2025 captured a blood moon and the Milky Way galaxy within the same field of view. The moon appears red from the bluer parts of its reflected sunlight being scattered by Earth's atmosphere.

While the sun, moon, and stars rise and set from east to west due to Earth's rotation, the moon's eastward revolution around the Earth causes its shadow to move from west to east during a solar eclipse.

Spikes of light around stars are artifacts of light bending around the mirror supports

Through diffraction, electromagnetic waves can bend around obstacles, as observed in the silver linings at the edges of clouds, where light should be blocked. Within reflecting telescopes, starlight diffracts around struts—beams holding a secondary mirror in place—and spreads perpendicular to them, creating pairs of spikes.

View photographs of solar eclipses on Mars, Jupiter, and Saturn caused by the moons of these planets blocking sunlight.

By identifying patterns in the periodic movements of the sun, moon, and Earth, ancient civilizations realized that identical eclipses repeat about once every 6,585 days, known as the saros cycle.

Research shows that during total solar eclipses, some animals change their behavior to match their nighttime activities.

Scientists used to speculate about life on the moon

In the 17th century, Galileo's observations suggested the moon could be inhabited, leading to fictional speculations about lunar life. In the 19th century, stories were published claiming the discovery of various creatures, including human bats. The Apollo missions in the 20th century explored the possibility of life there, but further exploration showed this idea to be less likely than before.

Moon 101: NASA's complete overview of our lunar companion

From modulating our tides to impact our climate, Earth's lone natural satellite plays a key role forming the planet's habitat. Before diving into the rest of the resources on this page, check out NASA's overview of the basics of the Moon—how it got its name, its size and distance from Earth, its structure, and much more.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

While solar eclipses were considered ominous throughout history, multiple cultures explained the celestial event as the result of mythical creatures nearly consuming the sun.

Voids in the northern and southern lights are known as black auroras

Appearing as dark rings or blobs against the illuminated sky, black auroras occur when there are holes in Earth's ionosphere—the upper atmospheric layer of charged particles created by solar ultraviolet rays. In these gaps—also known as anti-auroras—electrons ascend up into space, rather than spiraling into the atmosphere to collide with atmospheric gases and produce light.

Although the moon's dark spots were named "maria"—the Latin word for "seas"—in 1645, water was not confirmed on the sunlit surface of the moon until 2020.

Craters found on the moon and the calculated dates of these impacts, based on rocks returned by the Apollo missions, suggest that Earth was pummeled by asteroids for millions of years—a period known as the Late Heavy Bombardment.

Just as squeezing a grape causes it to bulge, the moon's gravity exerts an overall pressure that displaces water toward the opposite sides of Earth's equator, producing tides.

How the moon creates tides

Anyone who has visited large bodies of water virtually anywhere on Earth notices low and high tides occur at regular intervals, a process primarily driven by the moon’s gravitational pull. This explainer details how the motion of the Earth and Moon interact to create tides.

The faint triangle of light occasionally seen above the horizon, known as zodiacal light, is due to sunlight reflecting off ice and dust scattered throughout the inner solar system.

While the leading hypothesis for the moon's origin involves a Mars-sized object called Theia striking ancient Earth and forming from the resulting debris, it cannot explain why lunar isotope abundances match Earth.

Just as directly observing a solar eclipse without protective glasses can cause permanent eye damage, photographing an eclipse requires a specialized filter to prevent damaging your camera.

The accidental birth of radio astronomy and the benefits of a moon-based telescope

Detecting radio waves from distant celestial objects is complicated by noise from solar wind, which the nighttime side of the moon is shielded from. If lunar temperature extremes can be overcome, the environment may serve as an optimal future home for radio astronomy, a field that began in 1928 when a 30-meter-long directional antenna, mostly out of brass and wood, picked up signals from the Sagittarius constellation.

The majority of exoplanets—planets outside the solar system—have been discovered through mini-eclipses created when they pass in front of their host star and block some of its light from reaching Earth.

Moon's visibility is determined by its declination, equivalent to Earth latitude

The Moon's declination varies between approximately +28.7 degrees and -28.7 degrees, ensuring it rises and sets between latitudes of approximately 61.3 degrees north and south. This means there are places on Earth where the Moon is never visible above the horizon and places where it temporarily does not set.

Explore a collection of moon interactives from NASA, including a 3D lunar surface explorer, a tool for classifying moon rocks, and an interactive map for observing the moon each day of the year.

The first scientifically useful photograph of a total solar eclipse was taken in Königsberg, Prussia, on July 28, 1851, using a silver-coated copper plate with a light-sensitive chemical layer.

A map of the moon, using lidar

When planning to land on the moon, knowing the topography matters. This map of the lunar surface was created by using 6 billion measurements from NASA's Lunar Orbiter Laser Altimeter, a type of lidar. Check out the technically accurate depths of craters and ancient oceans on our beloved lunar neighbor with this fun, impressive map.

Visualize the path of every solar eclipse from 1900 to 2099 and see what each looks like when observed from different locations on Earth.

Eclipse glasses protect the eyes from overexposure to the sun's ultraviolet, blue, and infrared light, as a person's instinct to look away from the sun is diminished when it's partly blocked.

Why some people say the moon is made of cheese

Mental Floss digs into the history behind the fable, which dates back as far as the 1500s, when it was mentioned in "The Proverbs of John Heywood." Even NASA has gotten in on the joke, tweeting a (supposedly) doctored photograph showing the moon's expiration date.

Geological tremors on the moon provide evidence that it is shrinking

Apollo seismometers have collected moonquake data, which scientists have analyzed to map the moon's interior and reveal that fault slips producing tremors are the result of sublunar cooling and contraction. It also revealed that the moon's inner core is about 500 kilometers (311 miles) across.