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Comment by PeterCorless | Hacker News Reader

Voyager 1 is currently 22 hours, 32 minutes and 33.1467 seconds away. I want to celebrate when it is a "Light Day" away.

https://theskylive.com/how-far-is-voyager1

A prior thread calculated it to be November 18, 2026. [see here: https://news.ycombinator.com/item?id=31794292]

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The enormity of this statement is really blowing my mind. /If/ we could travel the speed of light, which we can't, it would still take nearly a day to get to Voyager 1, which seems both infinitely far given our current capabilities and remarkably close given how long it's taken to get that far.

No. If you could travel at the speed of light you would take no time to reach Voyager 1.

Actually, you could get anywhere in the reachable Universe.

For example, it takes only 29 years to from Earth to Andromeda galaxy assuming constant 1g acceleration for half of the trip and then constant 1g deceleration for the other half.

Wait why is the 1 LD from earth sooner than 1 LD from the sun? I'd expect it would be the opposite?

Because the earth is a bit closer to Voyager than the sun is.

If the earth is closer to voyager than the sun, then the 1 LD from the sun date should be sooner than the 1 LD from the earth date. But in the linked calculations it's later?

Given that the Earth orbits the Sun, I would expect it to swap every half a year. For one half of the year, the Sun should be ever so slightly closer to Voyager 1 than the Earth, and the other half of the year the opposite should be true.

However, considering that the Earth and the Sun are no more than ten light-minutes away from each other, I shouldn't think this would make much difference to our festivities :)

Earth orbits the Sun at an average distance of 149.60 million km [WP]

45 degree angle (see Quora animation): 150000000 * cos(45) = 79000000

Earth projection sits between Voyager and Sun.

"...travelling at around 61,500km/h ": 79000000/61500/24 = 53 days to add the equivalent of that distance in LD time.

Edit: huh, since Earth sits between voyager and the Sun, the LD distance is satisfied for the Sun first.

Yeah, that's why I'm consued why the LD from the sun is later than the LD from the earth.

The light delay to the sun is 8 min which means that the biggest light delay difference to voyager will be about 16min give or take if the sun is directly between earth and voyager. That’s more or less negligible when you are measuring 1 light day worth of delay.

That's the point: it's not negligible when you have to convert it to the distance this craft has to fly.

It's a bit of mental gymnastics, I suggest you do the exercise with paper & pencil to see what happens.

At most it would take Voyager about 190 days to travel 16 light minutes. Considering it’s been flying for 47 years and that it will take 3 more years for it to reach 1 light day of delay half a year more on top of that is pretty negligible in my book.

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