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Bioslug t1_j24i8v1 wrote

It says right in the article that this isn’t rare.

“The planet parade is not an extremely rare occurrence — it tends to happen at least every couple of years. In fact, the eight-planet alignment last happened in June.”

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stanspaceman t1_j251g2x wrote

You're mistaken. Yes the last one was also this year, but the next one isn't for another decade. They are quite rare.

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greengolfballs t1_j25ibbs wrote

The one earlier this year didn’t include Neptune or Uranus (which the author neglected to mention). Still counts as a “parade”, but 8 together is super uncommon. The next 8-parade (see my other comment) is in 2040 and the one after that is 800 years later.

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smurficus103 t1_j2537h1 wrote

It does take time for Jupiter and Saturn to line up

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Firestorm83 t1_j253n3x wrote

Let's say every decade; so that would have happened rougly 450.000.000 times in the earths lifespan. Wouldn't call that a rare occurence

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Zigazig_ahhhh t1_j25402h wrote

Idk man, if you go to the movies once a decade wouldn't you say you go rarely?

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Cpt_James_Holden t1_j2561ip wrote

Different time scales. A decade for me is like a millisecond for the solar system in terms of lifespan.

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No-Fail830 t1_j25bsxj wrote

Yeah but it’s rare to us which is who the information is being conveyed to. The earth doesn’t plan to read the article, nor does it give a shit.

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Zigazig_ahhhh t1_j25v2ln wrote

Okay but most people in here are humans, not solar systems.

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denada24 t1_j27zluq wrote

But, we aren’t known for having solar system lifespans. So, rare, indeed, for humans.

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stanspaceman t1_j25i7b2 wrote

Your algebra is very impressive but your ability to understand basic conversational quantities is lacking.

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YouthMin1 t1_j27t9zw wrote

After 2040 it’ll be 800 years before it happens again.

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greengolfballs t1_j25hdwm wrote

Which didn’t include Uranus or Neptune. If you read that article, it was only the planets you can see without a telescope: i.e. Mercury Venus, (Earth), Mars, Jupiter and Saturn. Still reasonably uncommon though, especially in that exact order.

Seeing any three planets in the same part of the sky is trivial. Happens all the time..

But seeing seven (plus earth) is exceptionally uncommon. It will happen again in 2040 and after that 2854.

Neptune and Uranus have the longest orbits (165 and 84 earth years respectively) so most of the time they’re not in sync AND you’ve got to wait for the other giants and inner planets to be on the same side of the sun too, so you can understand the rarity.

A parade is not the same as an alignment by the way. An alignment is when the planets (from earth’s perspective) line up within a narrowly defined margin of one another. If that margin is one degree of arc for example, you could expect all 8 planets to align once every 13.4 trillion years. Which is to say, never, because that’s 1000x the current age of the entire universe. On the plus side, the sun will become a red giant, engulfing Mercury and Venus within that time, meaning fewer planets and thus slightly higher chances of alignment. Then again the earth will be consumed too, so, you know, c'est la mort.

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cursed_rumor t1_j28wg87 wrote

well gee i better hope its not cloudy that day in 2040

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