An alignment of all the planets is impossible due to differences in the tilts of their orbits.

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.

You could fit every planet in the solar system in the space between the Earth and the moon when they are farthest apart.

Simulate the precession of Mercury's perihelion—the gradual shift in the closest point of Mercury's path around the sun as its elliptical orbit rotates.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

The solar system's planets orbit in the same direction in a nearly flat disc because the particles that made up the gas cloud from which the system formed had an initial, overall plane of rotation.

Planets' high orbital speeds prevent them from falling into their host star

Neptune is the farthest planet from the sun, orbiting 30 times farther than Earth and taking 165 years to complete one revolution.

The sun does not just get lower or higher in the sky throughout the year—it traces a figure-eight pattern called the analemma.

Dwarf planets do not meet all three necessary criteria to be considered planets: orbiting the sun, being round, and clearing their orbits of similarly-sized objects.

Earth's smooth, continuous motion as it orbits the sun prevents detectable motion

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.

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.

On planets in systems with two stars, such as the fictional Tatooine from 'Star Wars,' observers would see overlapping rainbows and double rainbows.

Evidence for a ninth planet in our solar system

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.

The 45 planets astronomers think are most likely to host alien life

View stunning geometric patterns created by drawing lines between the orbital positions of planets over many years.

Are there any planets in the universe that aren’t round?

Excluding using another planet's gravity to redirect the object, it takes less energy for a spacecraft to leave the solar system than to hit the sun.

In 1676, Danish astronomer Ole Rømer determined that light did not travel instantaneously by observing a delay in the appearance of solar eclipses on Jupiter when it was farther from Earth.

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

Explaining why the Earth wobbles

The Earth would tear apart the moon if it were less than one-twelfth its current distance from the planet.

Except for Mercury, every planet in the solar system experiences auroras

Rotating objects pull on spacetime, the underlying fabric of the universe—a conclusion validated by four of the most spherically perfect objects ever crafted.

The moon moves 3.8 centimeters (1.5 inches) farther away from Earth each year.

Instead of the tectonic plates found on Earth that produce earthquakes, volcanoes, and other geological activity when they interact, Mercury, Mars, and the moon have continuous, unbroken shells of rock called 'stagnant lids.'

Changes in Earth's orbital cycles influence the timing of ice ages

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.

Grasp the earth's orbit around the sun with this interactive

Through 2025, two-thirds of known exoplanets—planets that orbit stars other than the sun—have been detected via transits, where the objects cause periodic, consistent dips in their host star's brightness by passing in front of it.

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

Earth's rotation rate constantly changes, which drove the need for leap seconds to synchronize a solar day with timekeeping tools.

Replacing the sun with a black hole of identical mass would not change Earth's orbit, but life on Earth would collapse rapidly.

GPS satellites would become significantly inaccurate within hours if they didn't recalibrate according to Einstein's theories of relativity.

Asteroids are often unobserved until they are days away from Earth

There are places on Earth where the moon never sets and others where it never rises for days at a time throughout the year.

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

Everything you need to know about the planets in our solar system

An overview of Venus, from its retrograde rotation to its volcanic surface

Humans tend to imagine aliens as humanlike, but that's probably unlikely. Three different hypothetical planets show how aliens' bodies could take many forms.

How its uneven rotation produces the sun's 11-year cycle and flips its magnetic poles

A map of every object in our solar system

Galileo's Jupiter discovery shattered Earth-centered universe beliefs

No map of the Earth is perfect because each introduces inaccuracies in the shape, size, or orientation of landmasses and oceans by trying to flatten the planet's curved surface.

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.

Visualize chaos with the orbit of three or more objects bound by gravity

Why the sun's equator rotates once every 24.5 days, but the poles take over 34 days

Simulations show unidentified asteroids around Venus may pose a threat to Earth