Just before and just after a total solar eclipse, sunlight can pass through uneven terrain on the lunar surface, producing disconnected bits of light around the moon called Baily's beads.

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.

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.

The moon's gravity exerts an overall pressure that displaces the oceans toward the opposite sides of Earth's equator, producing tides.

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.

Light echoes are expanding shells of reflected starlight

Just as sound waves reveal the location of obstacles by reflecting off them, pulses of light emitted by stars illuminate rings of interstellar dust, giving the appearance of ejected material as the light travels outward.

If the moon were less than one-twelfth its current distance from Earth, the planet's tidal forces would overcome the moon's internal gravity, tearing it apart and forming a ring of debris.

Simulating the moon's surface in the desert

And why is the next cohort headed there? The geological conditions in Flagstaff, Arizona, can easily echo those of the moon, making the area a prime spot to train astronauts. This article explains how scientists crafted these training grounds and why astronomers are drawn to the nearly century-old city.

The moon's little-known, incredibly thin atmosphere

Earth's colorless, lifeless moon is often portrayed as devoid of an atmosphere. However, this fascinating article describes the very thin layer of gases floating above the surface of our celestial neighbor, a layer so thin it's technically known as...

Visualizing Earth's space garbage

An unsavory byproduct of humanity's brilliant exploration of space, the Moon, and more, is the rapid production of space debris floating around in orbit. Its estimated over 25,000 objects are in orbit, a number that grows everyday as satellites are decommissioned, rockets enter orbit, and more. Now, you can visualize what this debris looks like from a zoomed-out perspective with this brief video.

Photographer catches a 'once in a blue moon' shot

A rare "super blue moon" occurred in August 2023, a phenomenon which will not occur again until 2037. Photographer Andrew McCarthy caught a stunning image of the larger-than-normal orb with an ironic twist: a JetBlue flight silhouetted against the...

In the third century BCE, the Greek astronomer Aristarchus of Samos estimated the distance to the moon using geometry after measuring the length of Earth's shadow during a lunar eclipse.

Astronomers can identify systems with pairs of orbiting stars by observing recurring dips in the system's brightness as the stars eclipse one another.

Understanding ball lightning remains an area of active research

Observations of glowing orbs of light that appear during or after thunderstorms have been documented since at least the 12th century, but their rarity and short lifetimes have made their study challenging. Some theories suggest they form when lightning vaporizes pockets of gases in the air or certain materials on the ground.

In 2025, the European Space Agency created the first artificial solar eclipse in space when one spacecraft cast a shadow onto another spacecraft to enable observations of the sun's outermost atmosphere.

Aristotle discovered that Earth was spherical by observing the round shadow it cast on the moon during lunar eclipses and by noting that different constellations were visible from different latitudes.

A solar eclipse viewer can be made from everyday objects, such as a cereal box, aluminum foil, tape, and paper, to safely view the cosmic event.

How to sight the new crescent moon that starts Ramadan

Ramadan doesn't begin on a fixed date. Instead, it begins when a crescent moon is visually confirmed. The Royal Museums Greenwich explains the astronomy behind the sighting, including the conditions that must be met: the sun must be below the horizon, the moon must be above it, and the two must not be within the Danjon Limit (roughly 5 to 7 degrees of separation in the sky, as shown below).

Global eclipse tourism is a multibillion-dollar industry, with the 2024 total solar eclipse across North America estimated to have generated $6B in economic activity across regions along its path.