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olearygreen t1_j23zaqv wrote

Reply to comment by otter111a in Every planet in the solar system visible in rare "planet parade" by scot816

Wait… how? Wouldn’t that require all planets to have the same speed traveling around the sun? You need the inner planets between earth and sun, or behind the sun from our perspective which sure I can see that happening all the time unless they are hidden behind the sun itself. But the outer planets would need to be behind the sun from earth’s perspective, no? If they are on “our side” of the sun then we cannot see them together with the inner planets?

I need an ELI5 picture or video explaining to me how this is not a rare event.

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ChaoticAgenda t1_j241t65 wrote

A "planet parade" doesn't have to be the same planets or same configuration each time. The parade can also be as small as 3 planets. So a parade happens when at least 3 of the 8 planets line up. That's not very uncommon.

However,
This planetary parade has 5 planets in it and that does make it notable and uncommon. The last one like it was in 2002 and the next one is expected in 2040, https://starwalk.space/en/news/what-is-planet-parade

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olearygreen t1_j246pi8 wrote

Well yes. Was talking about all of them. Technically from the moon at night you would see all planets with a bit of luck not getting blocked by earth.

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sanjosanjo t1_j24bhfo wrote

The article says that the other seven were in a line, and that it last happened six months ago. I remember a Redditor posted a picture he took during that event.

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otter111a t1_j2430qf wrote

I’m no expert. I just read this in an article.

Here’s a map.

https://www.theplanetstoday.com

Let’s logic this out. Right now and for quite a few years Jupiter, Saturn, Neptune, and Uranus will all be on the same side of the sun. Mercury would join them very frequently.

So really the problem becomes one of Venus and mars joining them on that side of the sun or at some apparent angle that it looks like they’re all grouped up from earth’s perspective.

Mars’ orbital period of 687 days would put it on that side every other year but then it would also linger there for an extended period. Venus would saunter into view and eventually Mercury would zip over.

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olearygreen t1_j246igz wrote

Awesome. This makes sense. I read it as it’s fairly frequent now because the outer planets are all on the other side hanging out, which is lucky but not frequent in galactic terms.

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sanjosanjo t1_j24c8ml wrote

The article says it happened six months ago, so that was probably when Mars was at the other end of this alignment.

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smurficus103 t1_j2549t0 wrote

The issue is Jupiter has a period of 12 years and saturn 29 years. They can be on opposite ends of the sky for quite a while, one visible in winter and one visible in summer

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