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Simultaneous transits of Venus and Mercury?
Is it possible for Venus and Mercury to be transiting the sun at the same
time? Assuming the two orbits are independent of each other, it should occur (though extremely rarely: millions of years between double transits probably or something like that). Thanks in advance, ACG |
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Simultaneous transits of Venus and Mercury?
CeeBee writes:
Andrew Goldish wrote: Is it possible for Venus and Mercury to be transiting the sun at the same time? Assuming the two orbits are independent of each other, it should occur (though extremely rarely: millions of years between double transits probably or something like that). You're right. What should be the problem preventing the two passing the Sun simultaneuosly as seen from Earth? The problem that currently prevents it is the non-alignment of the nodes of Mercury's and Venus' orbits. I do not know their precession rates, so I'm not in a position to say how long it might be before the nodes are aligned. But for such a thing to happen, you'd need (a) the nodes aligned to within some tight tolerance, (b) both planets near their nodes at approximately the same time, (c) both planets on the same side of the Sun, (d) the Earth aligned with both planets at that time. I wouldn't be surprised if it's never happened in the 4.5 billion year history of the Solar System. |
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Simultaneous transits of Venus and Mercury?
wrote:
The problem that currently prevents it is the non-alignment of the nodes of Mercury's and Venus' orbits. I do not know their precession rates, so I'm not in a position to say how long it might be before the nodes are aligned. But for such a thing to happen, you'd need (a) the nodes aligned to within some tight tolerance, (b) both planets near their nodes at approximately the same time, (c) both planets on the same side of the Sun, (d) the Earth aligned with both planets at that time. I wouldn't be surprised if it's never happened in the 4.5 billion year history of the Solar System. Well then, we'll just have to wait. |
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Simultaneous transits of Venus and Mercury?
"Andrew Goldish" wrote in message
... Is it possible for Venus and Mercury to be transiting the sun at the same time? Assuming the two orbits are independent of each other, it should occur (though extremely rarely: millions of years between double transits probably or something like that). Yes, it is possible, and it is not millions of years. There is an article "Simultaneous Transits," by J. Meeus and A. Vitagliano in the June issue Journal British Astronomical Association. They found two in the years 1 to 300,000, both well into the future. Clear skies, Alan |
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Simultaneous transits of Venus and Mercury?
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Simultaneous transits of Venus and Mercury?
"Stuart Levy" writes:
I browsed a bit but couldn't find any on-line references suggesting specific values for rates of node advance for Mercury or Venus. From the 1992 edition of the Explanatory Supplement to the Astronomical Ephemeris, p. 316, we find for J2000 for mean equinox and ecliptic of that date: Mercury's node = 48.33° - 4.4630"/year Venus's node = 76.68° - 9.9689"/year However, the inclinations are not constant, so these are not representative of the long-term behavior. For a double transit, you would want to search for times when the inclination between the orbital planes of Venus and Earth was a minimum. Then Venus transits would be frequent enough that nodal alignments would be long-lasting, opening up many opportunities for double transits. Incidentally, I've added an appendix about transits seen from other solar system planets to my paper on the black drop effect at http://metaresearch.org/home/viewpoint/blackdrop.asp. -|Tom|- Tom Van Flandern - Washington, DC - see our web site on replacement astronomy research at http://metaresearch.org |
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Simultaneous transits of Venus and Mercury?
Hi,
"Stuart Levy" writes: I browsed a bit but couldn't find any on-line references suggesting The Journal of the British Astronomical Association has an article on this in its current issue (Vol 114 No. 3). It is not available online however http://www.britastro.com/jbaa/114-3.htm So summarise, they list three simeltaneous and near similtaneous transits, though none of us will be witnessing them!: 13,425 (the year) Sept 17th 0345 Venus Sept 17th 1927 Mercury 69,163 July 26th 1647 Venus July 26th 2031 Mercury 224,508 Mar 27th 2259 Venus Mar 28th 0339 Mercury specific values for rates of node advance for Mercury or Venus. From the 1992 edition of the Explanatory Supplement to the Astronomical Ephemeris, p. 316, we find for J2000 for mean equinox and ecliptic of that date: Mercury's node = 48.33° - 4.4630"/year Venus's node = 76.68° - 9.9689"/year However, the inclinations are not constant, so these are not representative of the long-term behavior. They mention this in their paper and state that to account for this they used formulae from Simon J L et. al, `Numerical expressions for precession formulae and mean elements for the Moon and the planets` Astron.Astrophysics 282, 663-683 (1984) [ http://adsabs.harvard.edu/cgi-bin/np...6A...282..663S ] I hope this is of help. Cheers, ~Al -- www.irishastronomy.org |
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