M:

magnitude: numbers assigned to heavenly bodies indicating their relative brightness: the smaller the number, the brighter the object. The brightest star, Sirius, with a magnitude of -1.44, is brighter than a star of magnitude 0, which in turn is brighter than a star of magnitude 1, etc. The faintest object the eye can see is magnitude 6, about the brightness of the planet Uranus. The Hubble Space Telescope can see some galaxies as faint as 30th magnitude, 4 billion times fainter than the faintest object the human eye can see. In general, objects are 2.512 times brighter than objects one magnitude less. Thus, a first magnitude star is 2.5x2.5.x2.5x2.5x2.5 = 100 times brighter than a star of magnitude 6. Venus, the brightest object in the sky other than the Sun or Moon, has a magnitude of -4.4. The full Moon’s magnitude is -12.7, and the Sun’s magnitude is -26.75.

main sequence: a curve on the Hertzsprung-Russell diagram along which most stars are located. Stars on this curve are called main-sequence stars or dwarf stars. The horizontal axis of the H-R diagram is a star’s spectral type, and the vertical axis is its mass. While a star is fusing hydrogen in its core (as most stars do during their active life), both a star’s spectral type and its luminosity depend only on its mass, which is why the main sequence exists as a curve on the H-R diagram. Stars usually enter and leave the main sequence when they are born and when they die, respectively.

major aspect: the conjunction, opposition, trine, square & sextile; 360° divided by 1, 2, 3, 4 or 6.

Makemake: the third-largest known dwarf planet in the Solar System and one of the two largest Kuiper belt objects (KBO) in the classical KBO population. Roughly ¾ Pluto’s diameter it has no known satellites, making it unique among the largest KBOs. Its extremely low average temperature (about 30 K) means its surface is covered with methane, ethane and possibly nitrogen ices.

Discovered in 2005, it was initially known as 2005 FY9, but called “Easterbunny” because of its discovery shortly after Easter. In 2008 the IAU included Makemake in its list of potential candidates to be given “plutoid” status, a term for dwarf planets beyond the orbit of Neptune that would place the object alongside Pluto and Eris. Classified as a plutoid in July 2008, in accordance with IAU rules for classical Kuiper belt objects it was given the name of a creator deity. Makemake, the creator of humanity and god of fertility of the Rapanui, the native people of Easter Island, was chosen in part to preserve the object’s connection with Easter.

malefic(s): (now archaic) Mars and Saturn.

masculine (yang): assertive fire or air qualities; Aries, Gemini, Leo, Libra, Sagittarius or Aquarius.

mass: An object's weight (not its mass) is a measure of how much the Earth pulls on that object. Hold an object in your hand. You can feel the Earth pulling it. But that feel of weight is a result of an interaction between the Earth and the object. Isaac Newton established that all bodies in the universe attract each other with a force that increases as mass of the bodies increases. Thus an object's weight depends on two things: how much stuff is in the object itself, and much stuff is in the object pulling on it, in this case, the Earth. It follows that an object's weight is greater in the gravitational field of the Sun, and less in the gravitational field of the moon.

Newton realized that all objects have an intrinsic property that stays the same whether the object is on the Sun, the Moon, or the Earth. This intrinsic property of all objects, independent of where they are, is called the object's mass. And an object's mass can be obtained by taking its weight, which depends on how much a planet or star is pulling on it, and dividing that weight by the strength of the particular planet’s or star's pull.

Now Newton discovered that the Earth pulls on (or accelerates) all objects with the same amount of force. This is the gist of his apocryphal falling apple experience. If you were to drop 1 pound of feathers and a 1-pound lead ball from the same height in a vacuum, they would both hit the ground at the same time. Why "in a vacuum"? Because air resistance would impede the falling feathers more than the falling lead ball—but they are both being pulled on (or accelerated by) the Earth with one pound of force, which is experienced on the Earth as their weight.

Since the Earth's pull is constant on all bodies, it is easily calculated to be 32 feet/9.8 meters per second per second. The "per second per second" is because acceleration is a change in velocity, so the Earth's pull increases a falling body's velocity 32 feet per second every second. The Earth's pull on all objects can be divided out of the weight of any object. And when you divide an object's weight by the pull of the body in whose gravitational field you're measuring its weight (like the Earth's pull), you're left with its "mass" (the units of which are "slugs" in the English system).

Thus a body's mass is independent of the planet in whose gravitational field you're weighing it. So although its weight differs on the Sun, the Moon and Jupiter, its mass remains constant on those bodies. Mass is the amount of stuff in a body, not how hard a particular body or planet is pulling on that amount of stuff (which is its weight).

maximum elongation: elongation is the angle between the Sun and a planet as seen from the Earth. Maximum elongation is therefore the maximum angle a planet makes with the Sun as seen from the Earth. This only makes sense with the inferior planets Mercury and Venus, whose maximum elongations are 28° and 47.8° respectively.

MC: “medium coeli,” Latin for “middle of the sky”; the intersection of the local meridian with the ecliptic; the midheaven or the tenth house cusp.

meridian: any circle with its center at the Earth’s center passing through the observer’s zenith and the North or South Pole. The meridian is that “vertical circle” passing through the center of the Earth and perpendicular to the horizon that also passes through the north and south points on the horizon. It is also perpendicular to the prime vertical: the vertical circle passing through the east and west points on the horizon. The horizon and meridian planes quarter the local sky and form the 12 houses when trisected by planes perpendicular to the prime vertical and passing through the horizon’s north-south line (see page 231). All local meridians intersect the ecliptic at the tenth and fourth house cusps. The 24 standard time meridians are 15° apart and define the time within the irregularly shaped time zones around them.

Messier, Charles: French astronomer (June 6, 1730-April 12, 1817) known for his catalog of deep sky objects. First published in 1774 with 45 objects, it eventually came to include 103. Astronomers later found evidence that another seven deep-sky objects were observed either by Messier or his assistant Pierre Mechain shortly after the final publication. Accepted by most astronomers as Messier objects, all the designations M1-M110 are universally used today by professional and amateur astronomers. Since Messier was only interested in finding comets, this non-comet list was to help him from being frustrated by false sightings.

midheaven: the ecliptic degree most directly overhead; the intersection above the horizon of the local meridian and the ecliptic. The highest point in the sky on a planet’s path, it is also the tenth house cusp or medium coeli (MC). It is one’s point of maximum externalization: the social world most distant from intimate, personal life.

minor aspect: the semisquare, quincunx, semisextile, sesquiquadrate, quintile, biquintile, septile, biseptile, triseptile, novile or decile.

minor grand trine: two planets in trine with their midpoint occupied by a third planet sextiling both; has more energy than just a trine, but less than a kite with an opposition; a sixth harmonic syndrome.

minor house(s): the second, third, fifth, sixth, eighth, ninth, eleventh and twelfth houses; any house other than the angular houses.

minute ('): the 60 equal divisions of a degree of arc. In a chart, the digits before the little sign symbol accompany the planetary glyphs show the position of each planet in the sign by degrees. The digits after the little sign symbol refine that position to 60ths of a degree, or minutes (') of arc. The Moon and Sun both subtend an arc of 30' in the sky, which is why they appear to be the same size from the Earth and can exactly eclipse each other. Venus has an angular diameter of 1' at closest approach, and unaided, the human eye can resolve objects in detail about 1' across.

Moirae: the apportioners or The Fates, three ancient white-robed personifications of destiny controlling the thread of life: Clotho, Lachesis, and Atropos.

mutual reception: a condition in which two planets are each located in a sign ruled by the other. This is a beneficial condition, lending harmony and stability to each, and compensates for the detrimental signification otherwise occurring if either or both planets are in their detriment or fall.

mutable: the third and last sign in each season, associated with flexibility and versatility. Gemini, Virgo, Sagittarius and Pisces are mutable signs. A lot of mutable energy in a chart indicates suggestibility, flexibility and perhaps a lack of stability.

mystic rectangle: two pairs of oppositions whose ends are trine and sextile to each other.