The enormous distances in the cosmos impel us to think in a way different to our usual miles or kilometres per hour. For example in the Solar System, the distance between the sun and Earth is 96 million miles. Astronomers call this distance an  "AU". Therefore each planet has an AU depending on its distance from the sun,  Mars which is 1,524,000 miles from the sun on average would have an AU  of 1.524

However once we move outside the solar system, the distances become so huge that we must think in terms of light-years, that is, the distance light travels in one year. The speed of light is 186,000 miles per second, thus light will travel 5.88 trillion miles in one year. 

The closest star system to Earth, Proxima Centauri, is 4.25 light years away meaning light takes that long in years to reach us. This  star system is thus 4.25 multiplied by 5.88 trillion miles - that is, 25 trillion miles from us !  Therefore if we could hitch a ride on the fastest man-made object to date, known as the Parker solar probe at around 400,000 miles per hour, it would still take 7,230 years to arrive. 

Consider then the distances in the universe between, and to, stars and galaxies  involving millions and billions of light years !!. 

The closest galaxy to Earth is Andromeda (the graphic in the header at the top of the page) which is 2.5 million light years away, so even if we could travel at the speed of light, it would take us 2.5 million years to reach it. At 10% of light speed it would take 25 million years!

The Challenge of Interstellar Travel

Even at 400,000 mph, a human crew would not survive the journey, as it would span hundreds of generations. Scientists are currently exploring concepts like "Breakthrough Starshot", which aims to use ultra-light "Starchips" about the size of a paper clip and  propelled by lasers to reach 20% the speed of light (about 134 million mph). At that velocity, the trip to Andromeda would take only 20 years. 

Einstein's theory showed that mass increases as one approaches the speed of light. Therefore at light speed man's mass would be infinite, making travel impossible.

Would you care for a more leisurely journey to Andromeda?

Traveling on a commercial jet at 550 mph would take 5 million years

Traveling by car at 70 mph would only take around 41 million years !

or as my old maths lecturer  would say "The mind boggles"