Noon

Noon
From LoveToKnow 1911
NOON, midday, twelve o'clock. The O. Eng. non, Nor. non, Dutch noen, are all from Lat. nona sc. hora, the ninth hour, i.e. according to the Roman system, three o'clock P.M.

Local Noon
Local noon is defined as the time when the Sun undergoes an upper meridian transit, crossing the imaginary great circle on the celestial sphere that joins the celestial poles and the observers' zenith.

Use Noon or 12:00 Noon when you mean midday and you will be in good company. The term Noon was first used in the year 1140AD.
Use Midnight or 12:00 Midnight when you mean the middle of the night.

Mars Pathfinder at Noon
This true color image of the Pathfinder landing site shows the Martian surface as yellowish brown with only subtle variations. These colors are identical to the measured colors of the Viking landing sites.

noon gap: {gnomon gap or split noon} the gap in the hour scale of a dial to account for the finite thickness of the gnomon. It is positioned on the dial plate where the sun is in the same plane as the gnomon, i.e.

Noon is when the Sun reaches the highest point in its journey across the sky. It then crosses the north-south direction--in the northern hemisphere, usually south of the observer. Because the axis of the Earth is inclined by an angle e = 23.

Noon is the hour of 12:00 in an observer's local time zone, or more loosely, a time near the middle of the day when workers in many countries take a meal break....
at the one place is midnight
Midnight ...

High Noon
The need for a "Universal Time" or even a time zone is a recent one.

Noon Greenwich Mean Time is not necessarily the moment when the Sun crosses the Greenwich meridian (and reaches its highest point in the sky in Greenwich) because of Earth's uneven speed in its elliptic orbit and its axial tilt.

Noon
The phase diagram seems to show that a solar and lunar eclipse should happen every month but eclipses actually happen only twice a year. You can see why if you look at the Moon's orbit from close to edge-on.

"At noon the absorption is weak but in the evening it is much stronger," says Jessica Sunshine, Deptuy Project Investigator for the Deep Impact mission which also observed signatures of water and hydroxyl on the Moon.

Why the noon start, for J2000 and normal Julian, and not midnight, as most people are accustomed to? Well, two reasons.

P78-1 was in a noon-midnight, Sun-synchronous orbit at 600 km altitude. The orbital inclination of 96 degrees implied that a substantial fraction of the orbit was spent at high latitude, where the particle background prevented detector operation.

mean noon The instant the mean sun is over the upper branch of the reference meridian; twelve o'clock mean time.

noon (NASA Thesaurus / NASA SP-7, 1965) The instant at which a time reference is over the upper branch of the reference meridian.

2.08 At around noon local time, the sun is about overhead as viewed by an observer at...
Greenwich England
JPL
Venus
Mars
Timbuktu ...

Because Mercury's rotation and revolution are locked in a 3:2 relationship, a Mercurian day, from noon to succeeding noon, ...

Eratosthenes knew that on the summer solstice at local noon in the Ancient Egyptian city of Swenet (known in Greek as Syene, and in the modern day as Aswan) on the Tropic of Cancer, the sun would appear at the zenith, directly overhead.

If you were at the point labeled "noon," the Sun would be high in the sky, but the Moon would be on the horizon - it would be rising.

Eratosthenes knew that at noon on the first day of summer, observers in the city of Syene (now called Aswan), in Egypt, saw the Sun pass directly overhead.

He compared the midsummer's noon shadow in deep wells in Syene (now Aswan on the Nile in Egypt) and Alexandria. He properly assumed that the Sun's rays are virtually parallel (since the Sun is so far away ).

When the center of the sun is on an observer's meridian, the observer's local solar time is zero hours (noon).

A solar day on Mercury (for example, from one sunrise to another, or one noon to another) is 176 Earth days (exactly two Mercurian years). The eccentricity causes the apparent angular size of the Sun to vary by nearly 50 percent (from 1.

On any date during the year the sun appears directly overhead at high noon with in a band of locations encircling the earth. This band is bounded on the north by the Tropic of Cancer which is 23.

Latitude was measured in the past either at noon (the "noon sight") or from Polaris, the north star. Polaris always stays within 1 degree of celestial north pole.

From solar noon to solar noon, the Earth rotates about 361 degrees in 24 hours. Our planet needs to rotate another degree -- for a total of 361 degrees -- for the Sun to return to its noontime position on the meridian.

The Julian Date (JD), or Julian Day Number, is a running count of days that starts at noon on January 1, 4713 BCE of the Julian Calendar. The date changes at noon, Greenwich (Universal) Time.

On long days the sun rose north of east and climbed high in the sky at noon; on days with long nights the sun rose south of east and did not climb so high at noon.

Approaching local Martian noon, discrete white orographic clouds, identified as water clouds by the Mariner 9 spacecraft, are seen in Martian spring and summer forming on the upper slopes of the large volcanoes Olympus Mons 113° W, 18° N), ...

A system of counting days from noon 1st January 4713 BC. The name has nothing to do with Julius Caesar but was invented by the mathematician Scaliger who named it in honour of his father, Julius Scaliger.

The interval of time in days (and fraction of a day) since Greenwich noon on Jan. 1, 4713 BC.

The tropic of Capricorn, the latitude at which the Sun appears overhead at noon on the winter solstice, which occurs between December 21 and 22, got its name because in Greek times the Sun was passing through Capricornus on this date.

The warmest regions occur near local noon. The ring of mountains surrounding the 540-mile diameter impact basin Argyre can be seen in the early afternoon in the upper portion of the photo.

Definition: high sun: The condition of the sun being directly overhead (analogous to noon) which eliminates shadows on the surface.

The Sun's magnitude at noon is about -26.7, but at the horizon, it would only be in the order of -15.8, a loss of brilliance almost 23,000x from that of noon. In addition, reddening would be very prominent.
REFRACTION ...

At Greenwich, apparent Solar noon varies between 11h44m05s and 12h14m19s. Maximum contribution from Earth's orbital eccentricity, ~ 8 min; from Earth's obliquity, ~ 10 min. Apparent and Mean Solar Time agree 4 times a year. [H76] ...

The tropic of Cancer is the latitude on Earth at which the Sun appears overhead at noon on the summer solstice, June 21.

Julian date The number of days since noon on 1st January 4713 B.C. It is useful for astronomical observations as it saves confusion with other calendars.

For you in Topeka, the altitude of the Sun at noon is 73.5°, which is pretty high in the sky. In fact, that is as high as the Sun ever gets at that latitude.

At 1 AU, Earth receives 1 unit of sunlight; what we generally might associate with a bright sunny day at noon. How much sunlight would a spacecraft receive if it were twice as far from the Sun as Earth?

It could be used to determine the local noon and the seasons via the summer and winter solstices and the spring and fall equinoxes. They were standardized throughout the Chinese empire to be 8 "chi" or 2.4 meters.

The synodic rotation period of the earth with respect to the sun; that is, the length of time from one local noon, when the sun is on the meridian, to the next local noon.
solar flare - (n.) ...

Time zones eliminate the problem that local noon (defined according to the elevation of the ) actually occurs at a different time for nearby towns at slightly different longitudes, ...

Interval between two successive culminations of the Sun - i.e., the period from apparent noon to apparent noon. The apparent Solar day is longest in late December. [H76]
Apparent Solar Time ...

Each date has a Julian Day number (JD), beginning at noon, which is the number of elapsed days since January 1st, 4713 B.C. For instance, January 1st, 1993, was JD 2448989; January 2nd, 1993, was JD 2448990; and January 1st, 2000, was JD 2451545.

Try to make it clear in your mind how sunrise, sunset, noon and midnight are caused by your location on a rotating Earth. Then try to imagine how the Earth's rotation causes the stars to appear to circle Polaris through the night.

The Julian Day is the number of days since the year -4712. The Julian Day begins at 12:00 Noon Greenwich mean time.
Jumbled Terrain
Strangely disturbed regions of the moon opposite the locations of the Imbrium basin and Mare Oriental ...

01.07.10 - Local students gear up for the 2010 FIRST Robotics challenge this Saturday, January 9, from 9:00am to noon, at Cuyahoga Community College Unified Technology Center.
Related Sites
FIRST Robotics Competition → ...

Apparent Solar Time - Time kept according to the actual position of the Sun in the sky. Apparent solar noon occurs when the Sun crosses an observer's meridian ...

6,000-mile-per-hour
winds may have offset
the planet's hot spot
by 30 degrees from
the planet's substellar
"high noon" (more).

The bird would build a nest of twigs and leaves that would be lit by the noon sun. The Phoenix would then be consumed by the fire, but a small worm would emerge from the fire and grow into another Phoenix.

Julian Date (JD)
the interval of time in days and fraction of a day since 1 January 4713 BC, Greenwich noon.
K ...

So the real question is "why is the Sun in the sky at some times and not at others?" We can see that the Sun seems to move across the sky starting in the east in the morning, moving toward the south at noon, and then toward the west as the day ends.

involved observing (and predicting...see scientific method) the motions of visible celestial objects (mostly stars and planets). An example of this early astronomy might involve a study of the relationships between the "apparent height" of the noon ...

Because of precession, it is now in Aquarius though the idea is preserved in the Tropic of Capricorn which is the line around the northern hemisphere globe where the Sun is directly overhead at noon in mid-winter (see also Tropic of Cancer).