Mars Opposition Mars: The Uneven Halves of a Mars Cycle

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Mars opposition Mars is the moment moving Mars stands exactly 180° from the degree Mars held at your birth: transiting Mars opposite natal Mars. Natal Mars is fixed at one instant and never moves; only the Mars in the sky does. The opposition point is the halfway mark of your own Mars cycle, measured in degrees, between one Mars return and the next.

Halfway in degrees is not halfway in time. This page takes the same invented birth and the same thirty-year window as the Mars return page, finds every opposition, matches each one to the returns on either side of it, and measures the two halves. Over 2000 to 2030:

• Sixteen oppositions, fifteen of them a single pass. One, in 2003, came in three passes: forward, backward, forward.
• The halves were either about eight to nine months or about fifteen. From a return to the next opposition, or from an opposition to the next return, took 254 to 275 days when no backward loop of Mars fell in that half, and 437 to 455 days when a whole loop did.
• The long half switched sides. For some years the long half came before the opposition, for others after it. Each switch happened where a loop sat on the return or opposition point itself, the same places where a contact came in three passes.

Mars is often read as drive, effort and the way a person goes after things. An opposition to natal Mars is one optional moment for reflecting on that, set against what other people or outside demands ask of you. It causes nothing and predicts nothing.

Educational guide only. Astrologist.com has no transit tool: no transit calendar, return chart or timing report. The free birth chart shows natal positions only, and every date below was computed offline for an invented person.

The birth, the opposition point and the window

The birth and the window are the ones used on the Mars return page, reused unchanged so that the two pages describe the same Mars cycle for the same person. That birth was first chosen under a rule fixed before any Mars date was calculated, and nothing about the oppositions was looked at before reusing it.

• The person: invented; born at 10:20 local time in Antwerp on 15 August 1989, which with Belgian summer time is 08:20 UT.
• Natal Mars: 157.443855° before rounding, or 7°26'37.9" Virgo, and going forward by 0.633° per day. The chart keeps 157.44° and prints 7°26' Virgo.
• The target: the degree exactly across the circle, 337.443855°, or 7°26'37.9" Pisces. Every crossing on this page is of that one value.
• Thirty years examined: 00:00 UT on 1 January 2000 to just before 00:00 UT on 1 January 2030, while this person is 10.38 to 40.38 years old.
• Calculation: positions of Mars from astronomia's VSOP87B theory, which is what the chart itself calls, after converting Universal Time to ephemeris time in the chart's own way. An hour-by-hour pass located the crossings, each was then pinned down to better than thirty seconds, and every turning point was found independently to better than a minute. That is arithmetic precision, not a statement about how closely the model follows the real planet. Dates are UT; for anything after October 2026 they are what the same model projects, not predictions.

One path, two kinds of level. Mars's path is followed without resetting at 0° Aries. On that unbroken path every lap has a return level (natal Mars plus a whole number of laps) and, 180° further on, an opposition level. An opposition contact is the set of crossings of one opposition level while Mars stays within 30° of it, closed once Mars is more than 30° away before the first crossing and after the last. Each opposition is then matched to the return level 180° below it and the return level 180° above it on that same path. That is a match by position, not by counting "the third return" and "the third opposition", so a three-pass return or opposition cannot throw the pairing off.

Every opposition, with the returns either side

The times in the table run from the first crossing of the return before to the first crossing of the opposition, and from the first crossing of the opposition to the first crossing of the return after. Where a return or opposition had three passes, the figure from its last crossing is added in brackets. Return dates are repeated from the Mars return page only as anchors.

Sixteen oppositions and eighteen crossings: fifteen single forward crossings and one contact of three. Every return level that brackets an opposition was found, and each sits exactly 180° from it on the path; between every pair of neighbouring returns there was exactly one opposition.

Edges of the window. Mars entered the window at 27°34' Aquarius, 9.87° short of the opposition point, so the first opposition came on 13 January 2000. Its single crossing lies inside the window, but Mars was already within 30° of the point from 5 December 1999, so that contact opened before the window and is labelled as such; the other fifteen opened and closed inside it. The return before it, on 19 October 1998, is outside the window and is shown only as a supplementary anchor. At the end of the window Mars was 22.74° short of the opposition point again; the next crossing, on 29 January 2030, falls after the window and is not counted. No opposition in the window's last 22 months does not mean none follows.

Why the halves are so uneven

Mars spends most of its time moving forward at roughly half a degree a day or more. Roughly every 2.1 years it slows, turns backward for 60 to 81 days, then turns forward again. Those backward loops are tied to the Sun, not to anyone's birth (see retrograde planets and the Sun), and in this window there were 14 of them.

A half-cycle is the stretch of path from a return level to the next opposition level, or from an opposition level to the next return level: 180° either way. Sorted by whether a loop fell inside it:

A loop costs Mars time without gaining it ground, so a half that holds a loop takes about six months longer than one that does not. A full cycle, return to return, was usually one short half and one long half, about 1.94 years, which is why the opposition is seldom near the middle of the calendar interval.

Why the long half switches sides. Mars's loops come a little more than one lap of its own cycle apart, so each loop lands further round the zodiac relative to natal Mars than the last: in this window the middle of each loop sat 33° to 78° further on than the one before. While the loops fell in the half between return and opposition, the long half came before the opposition: for the oppositions of 2000, 2001, 2013, 2015, 2016, 2018 and 2028. While they fell between opposition and return, it came after: for 2005, 2007, 2009, 2020, 2022 and 2024. The switch-overs are the three places where a loop sat on one of the two points themselves. Around the three-pass returns of 2011 to 2012 and 2026 to 2027 both halves measured to the return's first crossing were short (256 and 267 days, 255 and 282 days), because that return began early, as the Mars return page shows.

From its first crossing to its third, the 2003 opposition took 115.6 days. That number is only the time Mars needed to go over the same degree three times; it is not an orb and not a period during which anything is in force. Mars never came to a halt exactly on the opposition degree, so no touch is listed: its closest turning point was the backward turn of 29 July 2003, 2.69° beyond it.

If the birth time were unknown

Without a clock time, all that is known is the date. In Antwerp, 15 August 1989 began at 22:00 UT on the 14th and ended just before 22:00 UT on the 15th. In that stretch natal Mars moved steadily on from 157.171156° towards 157.804600°, the value at midnight that closes the day: 0.633° in all, with no jump across 0° Aries. The opposition degree therefore covers the same 0.633°, half a circle away.

That band was then laid against every turning point of moving Mars in the thirty years, lap by lap, and against Mars's place at the first and last moments of the period. None of them falls inside it. The closest is the backward turn of 29 July 2003, 2.33° beyond the band, and the period's two ends are 9.60° and 22.47° clear. Any birth time on that date would therefore give the same oppositions in the same pattern.

As an extra spot check, the oppositions were found again for 145 trial birth times spaced ten minutes apart through the local day, with 23:59 added at the end. Every trial gave the same sixteen oppositions, crossed in the same directions. From one trial time to another the crossing dates drifted by 0.80 to 2.72 days, the largest drift belonging to the slow 2003 crossings. These are what the trial times showed, not hard limits. If the chart is given no birth time, it places Mars for local noon and shows no houses.

Rounding, and a second ephemeris

Rounding barely matters here. Working from the chart's stored 157.44° shifts the opposition crossings by 0.12 to 0.39 hours; working from the printed 7°26' Virgo, read as 157.4333°, shifts them by 0.32 to 1.08 hours. In neither case does any UT date or any count change. Values from 157.428° to just under 157.445° all print as 7°26' Virgo, and the closest turning point sits 2.69° from the corresponding opposition band.

For a second opinion, the Swiss Ephemeris was run alongside; nothing on the page was taken from it. Swiss has natal Mars 0.07 arc-seconds higher. At the 18 opposition crossings, Swiss Mars was never more than 0.46 arc-seconds from the chart's target degree, and recomputing the crossings with Swiss Mars changed none by more than 0.003 hours, using either version of the target. Swiss and the chart also agree on the 28 turning points to within 0.07 arc-seconds and 0.011 hours. Those differences describe this example only; they are not an accuracy guarantee.

Possible themes at a Mars opposition

Take these as starting points for thought rather than outcomes, and set them beside natal Mars's sign and aspects, plus its house if you trust the birth time:

• A single pass. A checkpoint halfway round your own Mars cycle: how the way you go after things sits beside what others want from you.
• A three-pass opposition. Some astrologers treat the forward, backward and forward crossings as one question revisited over a few months rather than met at one moment.
• The uneven halves. If you track your own cycle, the long and short halves are a reminder that "halfway" is a position, not a date.

These are interpretive patterns, not destiny. This page does not predict events or account for them after the fact, and it does not suggest that Mars opposite natal Mars leads to conflict, accidents, success, or any particular outcome for health, money, work or relationships.

For the full list of this person's returns, see the Mars return. The same moving Mars measured against fixed natal points other than Mars is in Mars transits to natal Sun and Mars transits to natal Venus. The slower versions of the same halfway point are Jupiter opposition Jupiter and Saturn opposition Saturn, and Mars moving through the houses is in Mars transits through the houses.

Working it out for your own chart

1. Find natal Mars on the free birth chart, convert it to degrees counted from 0° Aries, and add 180° to get your opposition degree (subtract 360° if the sum passes 360°). The printed minute covers a narrow range, so keep that in mind.
2. Pick your years first. With a Tropical ephemeris, write Mars's position down as one running figure that does not restart at 0° Aries, backward stretches included, and mark on each lap where it passes your natal Mars degree and your opposition degree.
3. For each crossing, note the date and whether Mars was going forward or backward. Crossings of the same lap's degree with Mars staying inside 30° of it count as one event. Flag any event that started before your first year or is still going at the end.
4. Match each opposition to the return half a lap below it and the return half a lap above it on that running figure. Do not simply pair the third return with the third opposition. Then count the days from first crossing to first crossing.
5. Note each backward loop's two turning degrees. The half-cycle that holds a whole loop will be the long one, and a loop with your return or opposition degree between its two turns will give that event three crossings.
6. Not sure of the birth time? Work out natal Mars at the start and end of your birth date, add 180°, and see whether any turning point, or Mars at either end of your years, lands in that band.

Behind the scenes, the free chart has no date limit for Mars, and the site's tests hold its Mars against Swiss at noon on each day between 25 December 1919 and 8 January 2061, matching every turning point to a Swiss one. In the test run for this batch the worst noon difference was 2.22 arc-seconds, with a root mean square of 0.31, and the 132 turning points matched to within 0.012 hours at worst; the tests would fail beyond 0.05°, beyond a stricter 8 arc-seconds, or beyond 0.025 hours. Those tests are about positions and turning points, not transit dates, and a model projection that passes them is still not a prediction.

To do all this without software, see reading transits by hand. Ask the Astrologist will gladly go over your natal Mars, or opposition dates you have worked out, but it does not produce transit dates.

Related articles

• Mars Return (the same Mars cycle's starting point)
• Mars Transits to Natal Venus
• Mars Transits to Natal Sun
• Jupiter Opposition Jupiter (another planet's opposition to its own natal position)
• Saturn Opposition Saturn (another planet's opposition to its own natal position)
• Retrograde Planets and the Sun
• Mars Transits Through the Houses
• What Mars Signs Mean
• Life-Cycle Transits Overview