Autumn

Autumnal Equinox
The autumnal equinox occurs around 22 September each year, although this is only autumn for observers in the Northern Hemisphere.

Autumnal Equinox
The date (near September 22 in the northern hemisphere) when night and day are nearly of the same length and crosses the celestial equator (i.e., 0) moving southward (in the northern hemisphere).

Lacus Autumni
Lacus Autumni (latin for "Lake of Autumn") is a region of lunar mare that lies near the western limb of the Moon. Along this side of the lunar surface is a huge impact basin centered on the Mare Orientale.

The Spring and Autumn Equinoxes
A diagram showing how the Sun moves through the sky on an equinox.
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The spring and autumn equinoxes occur around March and September 21.

Star Science in the Autumn Sky

3. Measure Delta Cephei for a month Once students get the hang of it, they can find and measure the brightness of Delta Cephei in a few minutes.

Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter, usually in late September or late March when the arrival of night becomes noticeably earlier....
, not long before winter
Winter ...

Autumn Sky East:
sky view,
reverted sky view,
sky view with inlined constellation ...

Autumnal equinox
the point on the celestial sphere where the sun crosses the celestial equator from north to south. The time when the sun is at the autumnal equinox defines the first day of autumn. This happens on about September 22 each year.

autumnal equinox
The point at which the Sun crosses the celestial equator moving southward. It occurs around September 22 and marks the first day of autumn in the Northern Hemisphere.

Autumnal Equinox
The place where the Sun crosses the celestial equator heading south.
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Autumnal Equinox - The point in the sky where the Sun appears to cross the celestial equator moving from north to south. This happens on approximately September 22 ...

autumnal equinox
the time of year around September 23 when the sun crosses the celestial equator heading south
averted vision ...

autumnal {fall} equinox: see equinoxes.
axis (of the Earth's rotation) or polar axis: the line running through the true North and South poles about which the Earth rotates.

AUTUMNAL EQUINOX
Equinoxes are days in which daytime and nighttime are of equal duration. The two yearly equinoxes occur when the Sun crosses the celestial equator.

The autumnal equinox occurs at the moment that the Sun passes directly overhead at the Earth's equator on its way from the Northern to the Southern Hemisphere. Coming at 12:55 a.m.

This autumn a bright star will begin to fade in a curious transformation that occurs every 27 years, and this time the help of citizens will be called upon.

Emilie Autumn, Juliet
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Best seen: Autumn (northern hemisphere), spring (southern).

Notable Features: Saturn Nebula is one of the brightest planetary nebulae in the sky.

Spring, summer, autumn and winter are the names of the four seasons on Earth. Image Credit: NASA
Caused by Earth's tilt, a season is one of the four quarters into which the year is commonly divided: spring, summer, autumn or fall, and winter.

equinox See autumnal equinox and vernal equinox.
escape speed The speed necessary for an object to escape the gravitational pull of an object. Anything that moves away from the object with more than the escape speed will never return.

autumnal equinox specific moment in the year (on September 22) when the Sun is directly on the celestial equator, moving south of the celestial equator.

September equinox = autumnal equinox. sequencer A mechanical or electronic device that may be set to initiate a series of events and to make the events follow in a given sequence. See program.

March 21, when the sun's declination changes from south to north, is called vernal equinox, March equinox, or first point of Aries; that point occupied on or about September 23, when the declination changes from north to south, is called autumnal ...

AUTUMNAL EQUINOX. The equinox that occurs in September. BARTEL'S ROTATION NUMBER. The serial number assigned to 27-day rotation periods of solar and geophysical parameters.

Rising over the eastern horizon, Taurus's Pleiades star cluster announces northern autumn, telling of the cold months to come, when the group will soar high through the winter sky.

Harvest MoonThe Harvest Moon refers to the Full Moon that comes closest to the autumnal equinox, or the first day of autumn....Human Powered Clock DriveThink you need exotic materials and a machinist's know-how to get good astro photos?

Hipparchus made equinox and solstice observations, and according to Ptolemy (Almagest III.4) determined that spring (from spring equinox to summer solstice) lasted 94 + 1/2 days, and summer (from summer solstice to autumn equinox) 92 + 1/2 days.

Either of the two points (vernal, autumnal) on the celestial sphere where the ecliptic (which is the apparent path of the sun on the sky) intersects the celestial equator.

The Balance, obviously indicating the equality of day and night, is first mentioned as the sign of the Libra autumnal equinox by Geminus and Varro, and °b and tained, through Sosigenes of Alexandria, official re Scorpio.

Each Martian autumn, bright clouds form over the appropriate pole. Below this so-called polar hood, a thin cap of carbon dioxide frost is deposited during autumn and winter. By late winter, the cap may extend down to latitudes of 45°.

First, the star Antares (RA 16h 29m) is a bright red star, which anciently marked the autumnal equinox, that is, the place in the sky where the sun appears on the first day of autumn.

One afternoon it occured to Colpitts [one of the traveling scientists] that it was the night of the autumnal equinox, ...

At the autumnal equinox, about Sept. 23, the sun again appears to cross the celestial equator, this time from north to south; this marks the beginning of autumn in the Northern Hemisphere.

The two intersection points are the vernal equinox and autumnal equinox. The two points on the ecliptic which are farthest away from the equator are the summer solstice and winter solstice.

This composite of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) daily global images shows the early autumn dust storm (top 1/4 of the picture) sweeping east-northeast (toward upper right) across the northern plains.

When autumn and winter occur at closest approach, as is the case currently in the northern hemisphere, the earth is moving at its maximum velocity and therefore autumn and winter are slightly shorter than spring and summer.

Like folks in many other parts of the world, during the autumn the people of Greenwich set their clocks back an hour for the dark winter months and then set it forward an hour in the spring.

Interestingly, during late autumn the Sun, moving along the ecliptic, will be in Ophiuchus for 19 days. It enters Scorpius on November 23, leaves a week later for Ophiuchus on November 30 and enters Sagittarius on December 18.

Between the vernal equinox and the autumnal equinox the sun appears to rise north of East and set north of West. Its maximum northern position is marked by the summer solstice (the moment summer begins).

Autumn and Spring occur during the passage between these two points. It is interesting to note that the hottest temperatures in the Summer usually fall around a month or so after the point at which the tilt causes a hemisphere to be closest to the ...

From ancient times farmers knew that for most crops, you plant in the spring and harvest in the autumn.

To give you their full names, they are the Vernal Equinox, which is around March 21, and the Autumnal Equinox, which is around September 21. You may recognize these dates as the beginnings of the seasons of Spring and Autumn.

The other intersection of the Celestial Equator and the Ecliptic is termed the Autumnal Equinox. When the Sun is at one of the equinoxes the lengths of day and night are equivalent (equinox derives from a root meaning "equal night").

The caps at alternate poles wax and wane, creating periodic phenomena in the atmosphere (such as polar hoods and hazes that obscure the surface during the late autumn and winter) and changes at the surface.

Astronomer Edwin Hubble was studying an object in the autumn constellation Andromeda known as the Andromeda Nebula. Viewed through a telescope, it looks like a pinwheel, with bright streamers wrapping around a big bulge in the middle.

The Sun is in Pisces from March 13 to April 19, and it crosses the ecliptic on March 21, which marks the vernal Equinox, the first day of autumn in the southern hemisphere.

From the Earth's viewpoint therefore, the Sun reaches one point at a quarter, the other at three quarters of the way through the sidereal year: the vernal (spring) equinox is thus on or around 21 March, the autumnal on or around 22 September.

Hi, When a star (or source) is moving away from you, does it emit blue or red light; and what about when it is moving towards you? With respect to the autumn and spring solstices: Do we get more "red" light in spring or autumn, more blue light ....

The equinoxes are times at which the center of the Sun is directly above the equator, marking the beginning of spring and autumn.

This constellation is most easily seen in Autumn for observers in the Northern Hemisphere, but may be visible from June through February.

It is a metal-rich star, one with an abundance of elements heavier than helium. The autumn equinox, which marks the first day of autumn and used to be the first point in Libra, now lies in Virgo, close to beta Virginis.

Libra means "The Scales" or "Balance", so named because when the zodiac was still in its infancy, some four thousand years ago, the sun passed through this constellation at the autumnal equinox (21 September).

Aries is a northern constellation and the first one of the zodiac; it lies between Pisces to the west and Taurus to the east and can be seen climbing the eastern sky in the northern autumn. The Sun passes through Aries from late April to mid-May.

Old almanacs often give the traditional names for Full Moons but they are rarely used today with the possible exception of Harvest Moon, the Full Moon nearest to the autumn equinox and usually (but not always!) falling in the month of September.

Info: Can be seen in Middle Europe only during late autumn and early winter. None of the stars is particularly bright, but here you can find the Fornax star system, one of the closest galaxies.
Gemini (Twins) ...

The two great circles defined by the celestial equator and the ecliptic, which is defined as the plane of the solar system, cross each other at 2 points: at the vernal equinox (first day of spring) and the autumnal equinox (first day of autumn).

In the lower left, the first image, the image is of shortly after the autumn equinox in Saturn's Northern Hemisphere. The top right image is approaching the winter solstice in the Northern Hemisphere.

The weather has been particularly active during the past two months, as spring arrived in the southern hemisphere and autumn approached in the north.

Noticeably better or worse seeing is often associated with prevailing winds from a particular compass direction; bad seeing with cold nights and winds of autumn and winter, good seeing with increasing air humidity, a rising barometer, ...

Saturn's rings open up as it moves from autumn towards winter in its Northern Hemisphere.