The closest planet to Earth
On several occasions I met the interesting question Which planet is closest to Earth
and decided to answer it.
As a matter of fact any of the terrestrial planets can be the closest to Earth at any instant. But which planet is closest
to us most of the time ? To answer this question I generated positions of Mercury, Venus, Earth and Mars at 0h TT for all
dates, beginning AD 1001-Jan-01 and ending AD 3001-Jan-01 and compared distances at which the planets are. Two millennia
should be large enough timespan to answer the question. Most amazingly its neither Venus nor Mars, but it's Mercury that is
closest to Earth most of the time - 46.8%. Second place is for Venus - it's closest planet to Earth in 36.7% of the time,
and Mars is third with 16.5%.
During 2009 and 2010 closest planet to Earth at different periods can be found below. All times are in Terrestrial Time and indicate the first instant at which specified planet becomes closest to Earth. Please note: distances between planets centers of mass are used in this computation.
2009-Jan-01 00:00:00 Venus 2009-May-18 05:20:08 Mercury 2009-Jun-06 22:55:14 Venus 2009-Aug-06 14:18:38 Mercury 2009-Oct-19 11:15:58 Mars 2009-Dec-28 22:22:32 Mercury 2010-Jan-10 23:30:59 Mars 2010-Apr-03 00:57:29 Mercury 2010-Jun-15 08:04:59 Venus
The closest planet to other planets
Table below summarizes results for closest to each planet. In the first column is home
planet, in other columns
are other planets and percent of time they are closest one's. For instance, Mars is closest planet to Mercury during 1.4% of
the investigated period, while Mercury is closest planet to Mars during 34.4% of it. Lack of percentage denotes technical
impossibility given planet to be the closest planet. It might be curious to note that Uranus and Neptune are the only two
planets for which at different instants any planet might be the closest.
Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune
Mercury 72.9% 25.7% 1.4%
Venus 66.4% 27.3% 6.3%
Earth 46.8% 36.7% 16.5%
Mars 34.4% 32.2% 33.5%
Jupiter 14.5% 19.1% 25.7% 35.2% 5.5%
Saturn 8.8% 12.2% 17.1% 24.4% 36.7% 0.9%
Uranus 3.5% 5.6% 7.6% 12.0% 24.5% 32.4% 14.4%
Neptune 2.3% 3.8% 5.5% 9.3% 19.2% 27.8% 32.1%
Below are times of closest approaches between all planetary pairs during the two millennia timespan, AD 1001 - AD 3000. All times in Terrestrial Time, dates prior to 1582 are in Julian calendar.
Planetary pair Distance Calendar Date
mln.km.
Mercury Venus 39.100 2911-Nov-13 11:22
Mercury Earth 82.080 2942-Jun-14 02:41
Mercury Mars 144.188 1089-May-12 04:44
Mercury Jupiter 686.296 2615-Sep-12 23:00
Mercury Saturn 1296.871 1355-Feb-09 08:52
Mercury Uranus 2672.292 2556-Jul-20 17:12
Mercury Neptune 4407.886 2870-Oct-14 17:33
Venus Earth 39.463 1137-Nov-28 16:26
Venus Mars 97.748 2904-Aug-19 01:30
Venus Jupiter 630.604 2616-Feb-26 21:27
Venus Saturn 1235.308 1355-Jan-30 14:39
Venus Uranus 2622.892 2555-Jul-10 04:27
Venus Neptune 4347.127 2871-Jul-11 08:40
Earth Mars 55.651 2729-Sep-08 04:50
Earth Jupiter 589.507 2734-Oct-17 11:54
Earth Saturn 1195.818 1354-Dec-02 06:47
Earth Uranus 2581.866 2555-Mar-22 01:14
Earth Neptune 4307.074 2870-Nov-20 08:41
Mars Jupiter 525.458 2617-Mar-04 01:16
Mars Saturn 1104.805 1473-Nov-10 15:30
Mars Uranus 2482.187 2555-Oct-23 21:58
Mars Neptune 4230.109 1071-Mar-21 19:59
Jupiter Saturn 567.561 1504-Apr-24 20:54
Jupiter Uranus 1917.716 2977-Aug-07 09:06
Jupiter Neptune 3697.595 1089-Mar-04 03:03
Saturn Uranus 1302.509 1216-Apr-23 11:40
Saturn Neptune 3009.487 2491-Sep-22 01:29
Uranus Neptune 1460.984 2852-Aug-05 15:17