What is the speed of Earth in space?

What is the speed of Earth in space?

As we go about our daily lives, it’s easy to forget that we’re all hurtling through space at incredible speeds. Earth is constantly in motion, rotating on its axis and orbiting around the sun. In fact, we’re all living on a fast-moving spacecraft. But just how fast is our planet moving? What is the speed of Earth in space?

The answer is surprisingly complex, as the exact speed varies depending on the reference point. Questions about how fast the Earth, or anything, is moving are incomplete unless they also ask, “Compared to what?” Without a frame of reference, questions about motion cannot be fully answered. For example, when we say a car is going at 120 km/h, we mean that it travels 120 km across the Earth in one hour, ignoring the fact that the Earth itself is also moving.

Calculating the Speed of Earth in Space

The Earth is rotating on its axis and orbiting the Sun. Additionally, the Sun, along with our entire solar system, whirls around the center of our galaxy, the Milky Way. Furthermore, our galaxy and neighboring galaxies are rushing towards a structure called the Great Attractor, a region of space roughly 150 million light-years away from us.

The Great Attractor, with a mass 100 quadrillion times greater than our Sun and spanning 500 million light-years, is composed of both visible matter that we can see and the so-called dark matter that we cannot.

So, even when resting in your armchair, you’re flying through space faster than the fastest human-made object ever built. But how fast, exactly?

1. The Rotational Speed of Earth

The Earth is 24,900 miles (40,000 kilometers) in circumference at the equator. It takes 24 hours for the Earth to complete one full rotation. Therefore:

24,900 miles / 24 hours = 1,037 mph (1,666 km/h)

The rotational sped of Earth

This speed is the highest at the equator and decreases as you move toward the poles. At the poles, the rotational speed is effectively zero, as you are rotating in place once every 24 hours. For instance, if you are in South Florida, you are moving at approximately 1,000 miles per hour (1,610 km/h or 0.447 kilometers per second). This high rotational speed is one of the reasons NASA launches rockets from Florida.

The speed of Earth: star trails occur because of the rotation of Earth on its axis
Star trails above a towering mountain create a captivating sight. These trails are the result of long-exposure photography, capturing the apparent motion of stars across the night sky. This phenomenon occurs because the Earth rotates on its axis, causing stars to appear to move in circular paths around the celestial pole. The longer the camera’s exposure, the more pronounced the star trails become. This effect is especially prominent in areas with minimal light pollution and clear skies. Beyond their mesmerizing beauty, star trails visually represent the Earth’s rotation and the stars’ movement relative to our planet. Photo by Oliver Newbery on Unsplash

2. The Orbital Speed of Earth around the Sun

Earth lies at an average distance of 149.6 million kilometers (93 million miles) from the Sun. It takes 365.256 days to complete one orbit, known as a sidereal year, which is measured relative to the stars. This period is approximately 20 minutes longer than the tropical year due to the precession of the Earth’s axis. During this time, Earth travels a distance of about 940 million kilometers (584 million miles).

584,000,000 miles / (365×24 hours) ~= 67,000 mph

The orbital speed of Earth around the Sun

Therefore, the orbital speed of Earth averages about 30 km/s (30 kilometers per second, 108,000 km/h or 67,000 mph). At this speed, Earth could cover its own diameter in just seven minutes and the distance to the Moon in approximately four hours. For comparison, Apollo 11 took approximately 76 hours to travel from Earth to the Moon.

The orbital speed of Earth
Earth orbits the Sun at an average distance of 149.6 million kilometers (93 million miles). Completing one full orbit in 365.256 days, Earth travels about 940 million kilometers (584 million miles) each year. This results in an average orbital speed of approximately 30 km/s (67,000 mph or 108,000 km/h), fast enough to cross the planet’s diameter in seven minutes and reach the Moon in about four hours. Image: The sun shines above the Earth’s horizon [NASA]

3. The Sun’s Motion

Our Sun’s motion also affects the speed of Earth in space. The Solar System, located near the edge of the Milky Way, orbits the galactic core at a distance of about 25,000 light-years from the center. By measuring the speed of other galaxies moving towards or away from us, we can estimate our own orbital speed: the Milky Way completes one rotation approximately every 250 million years.

This gives the Solar System an average speed of around 230 kilometers per second (514,000 mph or 828,000 km/h). However, we can’t simply add this to Earth’s speed around the Sun because our motion is circular. Therefore, Earth’s speed around the galaxy varies between 447,000 mph and 581,000 mph (720,000 km/h to 936,000 km/h), depending on the time of year.

The speed of Earth - The Location of Sun in the Milky Way galaxy
Our Sun, located near the Orion Arm of the Milky Way, orbits the galactic center at approximately 514,000 mph (828,000 km/h). Image: Sun’s location in the Milky Way galaxy [NASA]

4. The speed of the Milky Way Galaxy itself

Today, some 13 billion years after the Big Bang, space has expanded significantly. The initial flash from the Big Bang has stretched into longer, lower-energy waves, such as microwaves and radio waves. These waves, now called the Cosmic Background Radiation (CBR), still fill the universe just as they did at the time of creation.

In the late 1940s, physicists predicted the existence of this background radiation, but without the equipment to detect it, the prediction was forgotten. In the mid-1960s, Arno Penzias and Robert Wilson, scientists at Bell Laboratories, accidentally discovered the CBR while working on communications satellite technology. Their discovery, later confirmed by other telescopes and rockets, earned them the Nobel Prize in Physics as it provided the most direct evidence for the Big Bang.

The CBR serves as a “frame of reference” for the universe, allowing us to measure our motion relative to it. In 1989, the COBE satellite was launched to measure this radiation, revealing that Earth is moving at 600 kilometers per second (1.34 million miles per hour) relative to the CBR. Our motion is roughly in the direction of the constellations Leo and Virgo, likely due to a massive concentration of matter in that area, known as the Great Attractor. This concentration of gravity pulls the Milky Way and neighboring galaxies in that direction.

The Great Attractor
The Great Attractor region, believed to be the gravitational center of the Laniakea supercluster, which includes over 100,000 galaxies such as the Milky Way, was scrutinized by the Hubble Telescope. This anomaly suggests a compact mass concentration thousands of times heavier than the Milky Way, exerting a detectable gravitational influence on galaxies and clusters across hundreds of millions of light-years. Image source: NASA

Summary: The Speed of Earth in Space

Overall, the Earth’s speed in space is around 370 kilometers per second (1,332,000 km/h or 827,666 mph) relative to the Cosmic Microwave Background (CMB). This speed varies depending on our position in the Earth’s orbit around the Sun and the Milky Way.

This speed is less than the Milky Way’s speed relative to the CMB toward the Great Attractor because the Sun is moving in the opposite direction. The difference in these speeds (600 km/s – 230 km/s) results in Earth’s speed of 370 kilometers per second relative to the CMB.

The overall speed of Earth in space ~= 370 kilometers per second (1,332,000 km/h or 827,666 mph)

Earth’s speed in space is around 370 kilometers per second (1,332,000 km/h or 827,666 mph) relative to the Cosmic Microwave Background (CMB)

Video: The Earth’s Relative Cosmic Velocities

Planetary scientist Dr. James O’Donoghue published a video showing the relative cosmic velocities of planet Earth and the speeds to scale.

O’Donoghue says “The speed of light is 350 times faster than all these velocities combined”.

The speed of Earth in space: The Earth’s Relative Cosmic Velocities. Video by Dr. James O’Donoghue.

Sources

M. Özgür Nevres

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