Our home galaxy, the Milky Way, sits inside a local cosmic neighbourhood filled with other galaxies — from tiny dwarf companions to the great spiral of Andromeda. Those neighbours are enormously distant by human standards: even the nearest major galaxy is millions of light-years away, so any hypothetical crewed voyage would require timescales far beyond a human lifetime.
Nearby galaxies and how far away they are
Some of the best-known galaxies close to the Milky Way are:
- Andromeda (M31) — about 2.537 million light-years away. Andromeda is the nearest large spiral galaxy and the Milky Way’s biggest neighbour in the Local Group.
- Triangulum (M33) — roughly 2.73 million light-years away, another spiral in the Local Group.
- Large Magellanic Cloud (LMC) — about 163,000 light-years away, a satellite galaxy visible from the Southern Hemisphere.
- Small Magellanic Cloud (SMC) — roughly 200,000 light-years away, another nearby dwarf companion.
- There are also many dwarf galaxies much closer than Andromeda — satellites orbiting the Milky Way at tens to a few hundred thousand light-years — but the distances above give a sense of scale for intergalactic travel.
How long would a spacecraft take?
Travel time depends entirely on speed. A few illustrative examples highlight the sheer scale:
- At Voyager-class speed (Voyager 1 travels about 17 km/s, ~61,000 km/h): reaching Andromeda would take on the order of 4.5 × 1010 years — tens of billions of years, far longer than the current age of the universe.
- At 10% of light speed (0.1c): a spacecraft would still need roughly 25 million years to reach Andromeda (distance expressed in light-years equals travel time in years at light speed, so divide the light-year distance by 0.1 to get years at 0.1c).
- At light speed (the ultimate limit) it would take about 2.537 million years to reach Andromeda — still millions of years and therefore well beyond practical human travel.
- Shorter trips to nearby dwarf galaxies or the Magellanic Clouds scale down accordingly: at Voyager speed the LMC would take on the order of a few billion years; at 0.1c it would take on the order of a million years.
Why intergalactic travel is so hard
Two facts make intergalactic voyages effectively impossible with foreseeable technology. First, distance: a light-year equals roughly 9.46 trillion kilometres, and galaxy separations are measured in hundreds of thousands to millions of those units. Second, energy and physics: accelerating a macroscopic spacecraft to even a sizeable fraction of light speed requires enormous energy, advanced propulsion concepts not yet demonstrated, and solutions for shielding, life support and communication across multi-generational journeys.
Even theoretical concepts — fusion drives, antimatter engines, beamed propulsion or breakthroughs in physics — would leave travel times measured in thousands to millions of years for intergalactic hops unless humanity achieves near-light speeds and solves profound engineering and societal challenges.
What we can do instead
For now, our knowledge of neighbouring galaxies comes from telescopes, space observatories and robotic probes within the Milky Way. Telescopes let astronomers map stars, gas clouds, dark matter and black holes in Andromeda and other galaxies; spectroscopy reveals their compositions, motions and histories. Robotic missions continue to explore our own Solar System and test technologies that — in far future scenarios — could form the basis for far longer voyages.
The distances between galaxies are staggering reminders of the universe’s scale. They also focus scientific effort on observation, modelling and incremental technological progress rather than on crewed journeys to other galaxies — a human excursion to another galaxy remains, for now, the stuff of speculative science fiction.
