The obvious answer is the same as the number of years the Earth has existed. However, orbit is as much a function of mass and the sun is continuously losing mass, so one would suspect there is a discrepancy between the Earth’s chronological age and the number of orbits it has completed. Anyone calculate how many?
This question is going to be difficult to answer:
Firstly, how long has the Earth existed? Or, at what point in the process of matter accretion did the Earth become the Earth? Was the Earth the Earth before the putative Theia hit to create the moon? Or do we wait until after the Late Heavy Bombardment? The Earth is still accreting matter, to a small degree.
Secondly, where did the Earth form? Some theories suggest that the giant planets migrated outwards, which process might well have affected the Earth.
Third, how accurate do you need your answer to be?
The answers to most of those questions are going to be arbitrary. But what isn’t arbitrary and I believe would provide most of the information the OP is looking for is: was the early Earth’s orbital period longer or shorter than it is currently, and by how much? And has it changed to its current value in a linear fashion, or did it change a fair bit early on and then mostly stabilize?
Yes, phrases like “the number of years the earth has existed” imply that the unit of measurement is the current length of a year, regardless of former orbital periods.
Can’t answer he OP, but given that the sun orbits the Milky Way about once every 200 million years and the Earth is just over 4.5 billion years old, the sun has orbited the galaxy @ 22.5 times.
I would say all of them.
Nah, snfaulkner, there are plenty of orbits of the Sun that the Earth hasn’t made. Like, for instance, all of the ones that Mercury has made.
I thought the Earth-Moon system were created fairly early on.
touche
Relevant article by the Bad Astronomer, in which he states:
I’m pretty sure this is negligible, considering we don’t know the age of the solar system to this precision anyway.
And, of course, that 1024 tons in the quote should be 10^24. It took me an embrassing number of rereads before the lightbulb went off in my head.
Oops, sorry. Superscript formatting got lost in cut & paste…
The Earth formed some time after the Sun and the giant planets. The Moon formed due to an impact with another planet some time after that. But these are just general statements and we can’t pin down any specific body’s formation to closer than a couple million years or so. Even if we had a video of the formation of the Solar System, it’d be impossible to pick out a point and say “here’s exactly where the Earth formed”. Or any other body. They all formed by gradual accumulation of smaller bodies, so there was no point where we could say “before this, it wasn’t a planet, after it was”. Even the Moon. The collision occured at a specific point, but that left a lot of debris in Earth orbit which gradually collected into a single satellite.
At least 39 and a half. That is all I can personally confirm.
I can personally confirm another dozen or so more than that.
(get off my lawn, youngster)
The trick is in the “sup.” To get 10[sup]24[/sup], you need to type 10(brackety thingy)sup(brackety thingy)24(brackety thingy)/sup(brackety thingy).
(for subscript, do the same thing with “sub” instead of “sup.”)
10[sub]24[/sub].
I’ll do you one better. You type:
10[noparse][sup]24[/sup][/noparse] to get 10[sup]24[/sup].
(This is where [noparse][noparse] and [/noparse][/noparse] come in handy.)
The latest figure for the age of the moon is 4.51 billion years, plus or minus 0.01 billion years. The age of a specific CAI (calcium-aluminum inclusion) from a specific meteorite has been measured more precisely than that–4.5622 billion years, plus or minus 0.00017 billion years.