Did the earth once have "true" 30 lunar days months?

Question

I have stumbled across a web-site, proposing that possibly a "30 lunar-days" month was what we actually had sometime in history.

Does anyone know more about the subject?
I am intrigued. Is this worth my time?

Note, I am not uneducated but know NOTHING about astronomy.


http://www.direct.ca/trinity/360vs365.html

Answer 1

Barely possible because the earth and the moon are changing speed because of tides and basically the earth is slowing down a few seconds a century. So a million years ago the earth was turning faster and moon was orbiting at different speed so there might have been 30 shorter days for the moon to get from new moon to new moon.
All of which is moot because in the time humans have been on earth, the times of the lunar quarters have been so close to a week as to establish the week.
The only reason for looking at a lunar month of 30 days is to make it fit with a year of 360 days exactly and make the 12 months invented to match the zodiac and 12 being convenient and there is no point to that but wishful thinking and some vague hope for a perfect creation.

Answer 2

29 days, 12 hours, 44 minutes and 3 seconds to be exact In lunar calendars, a lunar month is the time between two identical syzygies (new moons or full moons). There are many variations. In Middle-Eastern and European traditions, the month starts when the young crescent moon becomes first visible at evening after conjunction with the Sun 1 or 2 days before that evening (e.g. in the Islamic calendar). In ancient Egypt the lunar month began on the day when the moon could no longer be seen just before sunrise. Others use a reckoned moon (e.g. the Hebrew calendar), or use a tabular scheme (Ecclesiastical lunar calendar). Yet others run from full moon to full moon. Calendars count integer days, so months may be 29 or 30 days in length, in some regular or irregular sequence. But all lunar months approximate the mean length of the synodic month of approximately 29.53059 days (29 days, 12 hours, 44 minutes and 3 seconds). There are several different ways of expressing the lunar month. The Moon's orbital period in a non-rotating frame of reference (which on average is equal to its rotation period) is about 27.32 days (27 days, 7 hours, 43 minutes, 11.6 seconds). This is known as a sidereal month and is measured by observing how long it takes the Moon to pass a fixed star on the celestial sphere. A synodic month is 29.53 days (29 days, 12 hours, 44 minutes, 2.8 seconds) and is measured from New Moon to New Moon. A New Moon is defined to occur when the Moon has the same ecliptic longitude as the Sun, as seen from the center of the Earth: i.e. when the Sun, Moon and Earth are almost on one line. A synodic month is longer than a sidereal month because the Earth-Moon system is orbiting the Sun in the same direction as the Moon is orbiting the Earth. Therefore, the Sun appears to move with respect to the stars, and it takes about 2.2 days longer for the Moon to return to the apparent position of the Sun. The synodic month is the most common way of expressing the lunar cycle. An anomalistic month is the Moon's orbital period measured from perigee to perigee - the point in the Moon's orbit when it is closest to Earth. An anomalistic month is about 27.55 days on average. The tropical month is the time for the Moon to return to the same ecliptic longitude, i.e. measured from the equinox; it is slightly shorter than the sidereal month because of precession of the equinoxes. The draconic month or nodal month is the period in which the Moon returns to the same node of its orbit; the nodes are the two points where the Moon's orbit crosses the plane of the Earth's orbit. Its duration is about 27.21 days on average.

Answer 3

The idea of making our months 30 days long was proposed in the past (hundreds of years ago), but there are a number of problems with that.
The actual lunar month is not exactly 30 days long (29.5) so eventually the month is out of synch with the year.
In times when crops and annual rainfall, river flooding, or sunrise times was more important, what mattered in a calendar was the season, which is related to the sun and not the moon.
Its interesting reading (search on "calendar reform" or "lunar calendar") but its more esoteric than useful.

Answer 4

Not likely. At one time the "days" on Earth were much shorter than they are now (more rapid rotational rate), but our rate of rotation is slowing continually. If they are referring to rotational rate compared to the moon's orbital period, then at some point it would have been possible, but I doubt it. The rotational rate of Earth and the moon's orbital period have been changing continually throughout the history of the Earth/moon relationship.

A long time ago the orbital distance of the moon from the Earth was much closer and it moved around us very rapidly. As it moves away, its orbital period lengthens. What that means is, its siderial period as observed from Earth (now 27.3 days) and its synodic period (now 29.5 days) will increase until, at some point in the future, the moon's synodic period will become 30 days (but just briefly) and later its siderial period will match 30 days (also for a short time).

J.

http://www.jrichardjacobs.net

"The speed of the brain is inversely proportional to the speed of the mouth squared.

Answer 5

No, not at least in recorded history. A twenty eight day cycle is taken by the moon. The reason other days were added is because the length of a year is not evenly divisible by 28.