How Fast Are We Moving Through Space?

Relative to the cosmic microwave background, the closest thing physics has to a universal rest frame, our solar system is hurtling at roughly 370 kilometers per second. That is over 1.3 million kilometers per hour. But that single number hides a stack of motions layered on top of each other: Earth spinning on its axis, orbiting the Sun, the Sun circling the Milky Way’s center, the Milky Way drifting through its galaxy group, and the whole region being tugged by enormous concentrations of matter hundreds of millions of light-years away. Which speed counts as “our” speed depends entirely on what you measure it against, and each layer of motion reveals something different about the universe we live in.

Standing Still on a Spinning Planet

The slowest and most immediate motion is Earth’s daily rotation. At the equator, the surface moves at about 1,670 kilometers per hour, or roughly 465 meters per second. Move toward the poles and that speed drops; at around 45 degrees latitude (roughly the latitude of Montreal or Milan), it is closer to 1,180 km/h. At the poles themselves, you barely rotate at all, just turning in place once every 24 hours.

This speed is too slow to register in your daily life, but it is not trivial for engineering. Rocket launches take advantage of it: launching eastward from a site near the equator gives the vehicle a free velocity boost, which is one reason space agencies favor equatorial launch sites. It also matters for long-range artillery and weather systems, where the Coriolis effect, a consequence of living on a rotating sphere, deflects moving objects sideways.

Earth’s Orbit Around the Sun

Earth orbits the Sun at an average speed of about 30 kilometers per second, or roughly 108,000 km/h. That is about 65 times faster than the rotational speed at the equator. Because the orbit is slightly elliptical, this speed varies a little over the course of a year, reaching its peak in early January when Earth is closest to the Sun and slowing slightly in July when it is farthest away. The difference is small, only about 1 km/s either way, but it is measurable.

This orbital velocity is the reason stars appear to shift position very slightly over the course of a year, a phenomenon called stellar parallax. It is also connected to stellar aberration: the apparent tilt in the direction of incoming starlight caused by Earth’s motion, similar to how rain seems to slant toward you when you walk through it. Astronomers have been measuring annual aberration since the 1700s, and more recent work has explored measuring the aberration caused by the solar system’s motion relative to nearby stars as well.

The Sun’s Circuit Around the Galaxy

The Sun, along with the entire solar system, orbits the center of the Milky Way. Pinning down the exact speed of that orbit has been a decades-long project, and the answer depends on how you model the galaxy’s mass distribution. The generally accepted range is about 220 to 250 km/s. One model that accounts for both the visible (baryonic) matter near the Sun and the dark matter halo farther out arrives at a circular velocity of 222 km/s at the Sun’s distance from the galactic center.¹ Meanwhile, measurements of more distant objects using radio telescope techniques have recorded galactic rotation velocities in the range of 187 km/s at greater distances from the center, helping astronomers trace how the galaxy’s rotation curve behaves in its outer regions.²

At roughly 220 km/s, it takes the Sun about 225 to 250 million years to complete a single orbit around the galactic center, a period sometimes called a “galactic year.” The Sun has completed somewhere around 20 of these orbits since the solar system formed. Over that timescale, the Sun has passed through different regions of the galaxy, occasionally encountering denser spiral arms and different stellar neighborhoods. The speed itself, though, has remained relatively stable because the galaxy’s gravitational field at our distance has not changed dramatically.

The reason this orbital speed is so much higher than what dark matter alone would predict at the Sun’s location is that most of the mass near us is ordinary matter: stars, gas, and dust packed into the galactic disk. Dark matter dominates at larger scales, in the extended halo surrounding the galaxy, which is why rotation curves at the galaxy’s outskirts stay flat instead of dropping off the way they would if only visible matter were present.

The Cosmic Microwave Background and Our “Absolute” Speed

All the motions discussed so far are measured against something local: the ground, the Sun, the galactic center. But there is a way to measure how fast you are moving against the universe itself, or at least against its oldest light. The cosmic microwave background (CMB) is radiation left over from the early universe, and it fills all of space nearly uniformly. If you were perfectly at rest with respect to this radiation, it would look the same temperature in every direction. If you are moving through it, the radiation ahead of you gets slightly compressed (appearing hotter) and the radiation behind you gets slightly stretched (appearing cooler). This creates a “dipole” pattern across the sky.

The first hints of this dipole were detected in the late 1960s, when experiments at Stanford picked up a directional excess in the microwave radiation that was consistent with Earth having a large velocity on top of its known orbital and galactic motions.³ Decades of increasingly precise satellite measurements have refined the number. The accepted speed of the solar system relative to the CMB rest frame is about 370 km/s, and the Planck satellite confirmed this by detecting not just the temperature dipole but also subtler aberration and modulation effects in the CMB fluctuations, finding a velocity component of 384 km/s in the expected direction.⁴

That 370 km/s already includes the Sun’s orbital motion around the galaxy. When astronomers subtract the Sun’s galactic orbit and Earth’s orbital velocity, the residual tells them how fast the Milky Way itself is moving through the CMB frame. After correcting for the Sun’s galactic orbit, the Local Group of galaxies (the Milky Way, Andromeda, and their smaller companions) appears to be moving at roughly 620 to 630 km/s relative to the CMB. This is the number that sent cosmologists scrambling to figure out what, exactly, is pulling an entire group of galaxies at over two million kilometers per hour.

What Is Pulling Us, and How Fast

The Local Group’s motion at 620-odd km/s is far too large to be explained by any single nearby galaxy cluster. For decades, the leading candidate was the so-called Great Attractor, a massive concentration of galaxies in the direction of the Centaurus and Hydra constellations. The name sounds dramatic, and early analyses suggested it might be a single dominant source of gravitational pull. The reality has turned out to be more complicated and, in a way, more interesting.

Recent work using high-precision distance measurements shows that there is a strong flow of galaxies converging in the direction of the Great Attractor, with peculiar velocities peaking at roughly 1,000 km/s and converging to zero at about 70 megaparsecs (around 230 million light-years) from the Local Group. The modest spatial extent of this flow is consistent with the original Great Attractor model and aligns with the magnitude and direction of the CMB dipole.⁵ But the Great Attractor is not the whole story. Numerical models of galaxy motions within the local universe find that the Local Group’s motion in the center-of-mass frame of the surrounding region is about 420 km/s, leaving a residual of 240 km/s that must be accounted for by structures even farther away.⁶

An analysis of the total velocity budget finds that mass within about 450 million light-years accounts for only around 72% of the Local Group’s cosmic velocity, with a 38-degree directional offset from the observed motion.⁷ The remaining quarter or so of our motion is driven by even more distant structures: the Shapley Supercluster, a colossal wall of galaxy clusters some 650 million light-years away, is thought to be a major contributor. The picture that emerges is not of a single cosmic magnet dragging us along, but of a layered gravitational landscape where multiple superclusters tug from different distances and directions, with the net pull adding up to the velocity we observe.

Bulk Flows and the Large-Scale Velocity Field

The Milky Way is not unique in having a peculiar velocity. Across the observable universe, vast regions of space move together as coherent “bulk flows,” spanning hundreds of millions of light-years and carrying galaxies along at hundreds of km/s.⁸ These are not random jostlings. They trace the gravitational influence of the largest structures in the cosmos: superclusters, voids, and filaments in the cosmic web.

Measuring these bulk flows is one of the harder tasks in observational cosmology. You need precise distance measurements to thousands of galaxies to separate their “peculiar” motion (due to gravity) from the smooth expansion of the universe (due to cosmological expansion). Small errors in distance translate into large errors in velocity, and different surveys have historically disagreed about how fast and how far these bulk flows extend. The convergence point of our own local flow shifts depending on the spatial scale you look at: at small scales, the Virgo Cluster dominates; at intermediate scales, the Hydra-Centaurus region takes over; at the largest scales, the Shapley Supercluster becomes the main attractor.⁷ No single structure dominates the velocity budget at all scales, which makes the “how fast are we moving, and toward what?” question genuinely multi-layered.

Does the Expansion of the Universe Count?

When people hear that distant galaxies are racing away from us at thousands or even millions of kilometers per second, they sometimes assume that means we are moving that fast. But cosmological expansion is a different kind of motion. Space itself is stretching, carrying galaxies along with it. A galaxy a billion light-years away is receding from us not because it is flying through space at some enormous speed, but because the space between us is growing. This distinction matters because the “speed” of recession can exceed the speed of light for sufficiently distant galaxies, which would be impossible for any object actually moving through space.

So cosmic expansion does not really count as “our” speed in any physically meaningful sense. It is the growth of the metric, not an object’s velocity through a fixed background. The speeds that matter for the question “how fast are we moving?” are the ones that involve actual motion through space relative to nearby matter and radiation: Earth’s rotation, its orbit, the Sun’s galactic orbit, and the Milky Way’s peculiar velocity relative to the CMB.

Adding It All Up

Because these motions point in different directions, you cannot simply add the numbers together. Earth’s orbital velocity around the Sun, for instance, points roughly along the plane of the solar system, while the Sun’s galactic orbit is tilted about 60 degrees relative to that plane. The Milky Way’s peculiar velocity through the CMB frame points in yet another direction. The combined velocity at any given moment is a vector sum, and it changes as Earth orbits the Sun and the solar system orbits the galaxy.

The calculation of Earth’s velocity relative to the galactic rest frame requires accounting for its orbital position at any given time of year, along with the precession of the equinoxes, which shifts the orientation of Earth’s orbit very slowly over millennia.⁹ This level of precision is not just academic curiosity. Experiments searching for dark matter particles passing through Earth need to know their detector’s velocity through the galaxy to a high degree of accuracy, because the expected signal depends on how fast the detector is sweeping through the local dark matter halo.

For a rough hierarchy that captures the broad picture:

Earth’s rotation: about 0.5 km/s at the equator
Earth’s solar orbit: about 30 km/s
Sun’s galactic orbit: about 220 km/s
Solar system relative to CMB: about 370 km/s
Local Group relative to CMB: about 620 km/s

Each larger motion swamps the ones below it, and each points in a different direction. The net result at any instant is a specific velocity vector that astronomers can calculate and verify against the CMB dipole.

Can We Feel Any of This Motion?

No, and the reason is fundamental. Velocity through space, no matter how high, produces no sensation unless it changes (acceleration) or unless there is a medium to push against. You feel the car accelerate, not the car cruise at highway speed. Earth’s orbit is essentially free-fall around the Sun, and the Sun’s orbit is free-fall around the galactic center. At every scale, gravitational motion is locally indistinguishable from rest. Einstein’s equivalence principle guarantees that a freely falling observer cannot tell from local experiments whether they are moving or stationary.

That said, the motion is not entirely without physical consequences. The CMB dipole itself is a real, measurable effect: the sky is genuinely about 3.4 millikelvins warmer in the direction we are heading and 3.4 millikelvins cooler behind us. And there is a subtler implication. Some theoretical work has explored the idea that clocks moving at different velocities relative to the cosmic rest frame would experience slightly different rates of time dilation.¹⁰ In standard special relativity, only relative velocities between observers matter, and there is no preferred frame. But the CMB provides a natural reference: it effectively defines a frame in which the universe looks isotropic. Whether this constitutes a “preferred frame” in a deep physical sense remains debated, but the practical upshot is that our motion relative to the CMB is detectable through multiple independent methods, from temperature shifts to aberration patterns to modulation of the fine-scale CMB fluctuations.

Why the Numbers Keep Getting Refined

You might wonder why, after decades of measurement, astronomers are still publishing new values for these velocities. The answer is that each layer of motion involves different measurement challenges. Earth’s orbital speed is known with extraordinary precision because we can track the positions of planets and spacecraft to within meters. The Sun’s galactic orbital speed is harder because we cannot see the galactic center directly (it is hidden behind dust), so astronomers rely on indirect methods like tracking the motions of star-forming regions using radio interferometry.²

The peculiar velocity of the Local Group is the trickiest because it requires mapping the three-dimensional positions and velocities of thousands of galaxies across a substantial fraction of the observable universe. Distance measurement errors as small as 5% translate into peculiar velocity uncertainties of hundreds of km/s for individual galaxies. Only by averaging over large samples can astronomers beat down the noise. The surface brightness fluctuation method, which measures the graininess of a galaxy’s light to infer its distance, currently achieves about 5% distance accuracy and has been instrumental in confirming the flow pattern toward the Great Attractor.⁵

Future surveys mapping millions of galaxy distances and velocities will sharpen the picture further. But the broad strokes are now well established. We are spinning, orbiting, circling, and being swept along by gravity at a combined speed that depends on what you choose as “stationary.” Against the most universal benchmark we have, the ancient light of the CMB, our corner of the cosmos is moving at more than 600 km/s, with no prospect of slowing down anytime soon.

Leaving the Solar System at These Speeds

One practical consequence of all this layered motion shows up when engineers design missions that leave the solar system. A spacecraft headed to the outer planets or beyond does not just need to overcome the Sun’s gravity; its trajectory also inherits the solar system’s motion through the galaxy. For missions within the solar system, this hardly matters because everything nearby shares the same galactic orbital velocity. But for hypothetical interstellar missions, the galaxy-scale motion becomes part of the navigation problem. Even getting a spacecraft into a high-inclination orbit around the Sun, say to study the solar poles, requires carefully choreographed chains of gravity-assist maneuvers past the planets, precisely because the energy costs of changing direction at these speeds are enormous.¹¹ The dark matter halo surrounding the galaxy also factors into far-future trajectory planning: its gravitational influence subtly alters the escape velocity from the solar system depending on which direction you leave.¹ The fastest we have ever launched anything, the Parker Solar Probe at about 190 km/s during its closest solar passes, is still less than the speed at which the Sun circles the galaxy. Escaping the galaxy entirely would require overcoming a gravitational well shaped by matter we cannot even see directly.

1
Monthly Notices of the Royal Astronomical Society. When leaving the Solar system: Dark matter makes a difference
2
Journal of Physics: Conference Series. Rotation Velocity of the Milky Way Galaxy Based on VLBI Astrometry
3
Nature. Velocity of the Earth with Respect to the Cosmic Background Radiation
4
Astronomy & Astrophysics. Planck 2013 results. XXVII. Doppler boosting of the CMB: Eppur si muove
5
arXiv. Return to the Great Attractor: Strong Evidence for a Steradian-sized Flow Converging at ~70 Mpc within the GA Supercluster and Aligned with the CMB Dipole
6
The Astrophysical Journal. Galaxy Flows within 8000 km s−1 from Numerical Action Methods
7
Open Journal of Astrophysics. Revisiting the Great Attractor: The Local Group’s streamline trajectory, cosmic velocity and dynamical fate
8
ScienceDirect (Elsevier / Physics Reports). Large-scale peculiar velocities in the universe
9
Journal of Cosmology and Astroparticle Physics. The Earth’s velocity for direct detection experiments
10
arXiv. Cosmic Relativity: The Fundamental Theory of Relativity, its Implications, and Experimental Tests
11
Keldysh Institute Preprints. Ballistic design of spacecraft’s orbits using gravity-assist maneuvers in projects for studying the solar circumpolar regions from positions over ecliptic