Voyager 1, launched in 1977, is the farthest human-made object and is still sending data home.
The probe crossed into interstellar space in 2012 and is now more than 160 times farther from the Sun than Earth is. A radio signal from it takes almost a day to reach us.
Why is this true?
Voyager 1 runs on a nuclear battery that is slowly losing power, and instruments are being switched off one by one to stretch the mission. It carries a golden record with sounds and images of Earth, just in case.
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More about space
Space facts are mostly a lesson in scale. Days longer than years, storms wider than Earth, light that left its star before the pyramids existed — the numbers stop being intuitive very quickly. Every entry here comes from established astronomy and includes a short explanation of what causes the effect, so the fact holds up when someone asks the obvious follow-up question at the dinner table.