September 2014 Sky Watching

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Sun

As our planet revolves around the sun, the sun appears to rise and set in different locations along the horizon and appears at different heights in the southern sky at noon.  Twice during the year, the sun rises precisely east and sets precisely west.  As seen from the equator at noon, the sun appears overhead.  The sun never appears at the zenith, directly overhead, as seen from the mid-northern latitudes.  The moment when the sun appears above the earth’s equator is know as the “equinox,” signalling a shift of seasons.  From the autumnal equinox (northern hemisphere), the sun appears farther south, lower in the sky at noon, and rises and sets south of east and west, respectively, until the next equinox in March.  The equinox occurs at 9:29 p.m. CDT on September 22.

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This chart show the hours of daylight during September in the blue shaded area.  (Click all images in this article so see them larger.)  The red curve on the chart shows the daylight throughout the year. During the month, the Chicago area loses about 80 minutes of daylight.  The loss of daylight during the month is the backwards of the increase of daylight from March 10 through early April each year,

 Moon

Phase Date/Time Moonrise Moonset
First Quarter 09/02/14 (6:11 a.m.) 2:07 p.m. 12:09 a.m. (9/25)
Full Moon
(Harvest Moon)
09/08/14 (8:38 p.m.) 6:52 p.m. 7:04 a.m. (09/09)
Last Quarter 09/15/14 (9:05 p.m.) 11:38 p.m. 2:26 p.m. (09/16)
New Moon 09/24/14 (1:14 a.m.) 7:01 a.m. 6:54 p.m.
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

 Evening Sky

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Evening planets Mars and Saturn appear in the southwest as the month opens.  On the diagram above, a nearly first quarter moon appears in the region near Antares.  Mars and Saturn are to the lower right of the planet.  The two planets are about 5.5 degrees apart.

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By mid-month, the annual track of the Earth around the sun places the view lower in the southwest. Mars is moving east and by September 15, it is about 13 degrees east of Saturn and 9 degrees west of Antares. Watch Mars approach and pass Antares during the remaining days of this month.

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Mercury skirts along the western horizon during bright twilight during the month.  Use binoculars to look for it low in the west-southwest on September 21 when it is less than 1.5 degrees from Spica

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Late in the month, Mars passes the star Antares.  While the pair appear to be close, within about 3 degrees of each other, Antares is over 25 million times farther away than Mars.  Mars shines by reflected sunlight and Antares is shining as a very distant star.  While it appears small in our sky, Antares is large enough to cover the orbits of the inner planets in our solar system.  The chart above shows the passing of the planet and the star,along with the appearance of the crescent moon.

Sometimes Antares is known as the “Rival of Mars” because it has nearly the same color and brightness.  The Greeks knew Mars as “Ares,” their celestial manifestation of their god of war.  So Antares can be interpreted as “Rival of Mars,” “The Opposite of Mars,” or “Not Mars.”  Antares is not Mars.

Morning Sky

Venus, the brilliant Morning Star appearing in the eastern predawn sky, is rapidly disappearing into the glow morning light this month.  On September 1, Venus rises 1 hour, 15 minutes before the sun.  By month’s end, it rises merely 34 minutes before sunrise.  The planet passes superior conjunction, on the far side of sun, late next month and moves into the evening sky.  For more about Venus as a morning star, see this article.

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Early in September, Venus and Jupiter are over 15 degrees apart and the separation grows about 1 degree — twice the apparent size of the full moon — each day.  The chart above shows them on the morning of September 2.  Find a clear horizon to see Venus.

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Venus passes the star Regulus in bright twilight on the morning of September 5.  As the diagram above indicates, the pair appear low in the sky.  Find an observing spot with a clear eastern horizon.  Binoculars will help with the view.

As Venus disappears into the sun’s glow, Jupiter reigns as the bright Morning Star for the the remainder of 2014.  It shines in front of the dim stars of Cancer.  On September 1, it rises in the east-northeast at 4 a.m. and is about halfway up in the eastern sky as dawn approaches.

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The crescent moon is near Jupiter on the morning of September 20.  The pair is separated by about 6 degrees.

Solar System

sol_system_140915On the chart above, the planets visible without a telescope are shown along with Earth in their respective orbits around the sun as seen far above the solar system on September 15, 2014.  The planets move in a counterclockwise motion. The line between the sun and Earth indicate time, noon and midnight.  Venus and Jupiter appear on the morning side of the line.  Venus is approaching the “noon” line indicating that it is moving into the sun’s bright glow becoming invisible to us.  Mars, Saturn and  Mercury are in the evening sky.  Mercury always appears near the timeline making it difficult to view.  From Earth, it never appears in the midnight direction.

 

 

Venus, Jupiter, Orion and Sirius This Morning, August 28, 2014

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Brilliant Morning Star Venus and bright Jupiter appear in the eastern sky this morning during twilight. (Click the images to see them larger.)  Venus is now well past Jupiter.  The planetary pair is 10 degrees apart.  Venus is rapidly moving to the far side of its orbit nearly behind the sun.  During the next six weeks it rises later and appears lower in the sky.  It passes superior conjunction and moves into the evening sky later this year.  Venus appears dimmer than Jupiter as it is clearing a cloud bank in the image and is obscured by low-level haze.  Meanwhile, Jupiter appears higher in the east each morning.   The pair continue to separate.
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Orion and Sirius appear in the southeastern sky at the same time as Venus and Jupiter are in the east-northeast.   Sirius, the brightest star, appears near the horizon.  Jupiter, shining by reflected sunlight, appears about 40% brighter than Sirius.  Betelgeuse and Rigel, Orion’s brightest stars, above Sirius.

More about the planets:

Venus and Jupiter This Morning, August 15, 2014

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With a bright moon approaching last quarter high in the south, brilliant Morning Star Venus and bright Jupiter shine in the eastern sky this morning.  (Click the image to see it larger.)  This morning the pair is separated by about 3 degrees.  During the next three mornings watch Venus meet Jupiter.  On August 18, they are 1/3 degree apart!  That’s less than the apparent diameter of the moon!

More about the planets:

Venus and Jupiter This Morning, August 13, 2014

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Brilliant Venus and bright Jupiter appear low in the eastern sky this morning. (Click the image to see it larger.)  Jupiter is emerging from the sun’s glare as it passed conjunction on July 24.  Venus is rapidly fading into bright morning twilight.  Venus is rapidly moving eastward and overtakes Jupiter on August 18.  During the next few mornings the pair appear closer each morning. This morning they are about 5 degrees apart.

More about the planets:

Watching the Night Sky, August 2014

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In August the constellation Scorpius rides across the southern horizon.  This month, Saturn and Mars are in front of those distant stars.  Antares is the brightest star of the group, rivaling the color and brightness of Mars.  More about that next month.

Perseid Meteors

Besides the annual appearance of the Summer Milky Way and summer’s bright stars, the Perseid Meteors appear at mid-month. The meteoroids are bits of dust from Comet Swift-Tuttle.  The debris continues to orbit the sun.  During a few nights in mid-August, our planet intersects the orbital dust.  These meteoroids collide with the atmosphere and they vaporize as they zip into the atmosphere at over 30 miles a second.  From the ground we see a flash of light, a meteor or shooting star.   Perseids can be seen anywhere in the sky as they seem to emerge from a spot in the constellation that rises in the northeast early in the evening and appears nearly overhead a sunrise.  At their peak, observers may see one meteor a minute.  This year, the shower occurs at the time of the nearly full moon.  The shower peaks at 7 p.m. on August 12, during daylight hours in North America.  With the mornings of August 12 and August 13 illuminated by bright moonlight, only the brightest meteors are seen.  The best view of the event is from a reclining chair or a blanket.

Moon

NASA Photo

NASA Photo


Phase Date/Time Moonrise Moonset
First Quarter 08/03/14 (7:50 p.m.) 1:14 p.m. 11:55 p.m.
Full Moon 08/10/14 (11:09 a.m.) 7:00 p.m. (08/09) 5:47 a.m. (08/10)
Last Quarter 08/17/14 (7:26 a.m.) 11:26 p.m. (08/16) 1:54 p.m. (08/17)
New Moon 08/25/14 (9:13 a.m.) 6:15 a.m. 7:25 p.m.
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

Sun

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The amount of daylight decreases nearly 75 minutes this month.  As our planet continues its journey around the sun, the sunrise and sunset points change along with the time of each event.  The shaded area above shows the decreasing daylight during August.  (Click the image to see it larger.)

Evening Sky.

Mercury moves to the far side of the sun (superior conjunction) on August 8 and rapidly moves into the evening sky.  From the northern hemisphere,  it sets within an hour of sunset and largely lost in the sun’s brilliance.  On the evening of August 27, the crescent moon appears near Mercury.  Observers will need a good horizon and binoculars to find them.

Mars and Saturn are easily seen in the southwest.

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Early in the month, the moon moves through the region, making easy identification of the planets and bright stars in the region.  Here are the events:

  • August 2 — The moon is about 6 degrees to the upper left of the star Spica and 5 degrees to the right of Mars.  Saturn is nearly 13 degrees to the upper left of Mars.
  • August 3 — Tonight, the moon appears Mars, Saturn and the star Zubenelgenubi.  It is nearly 8 degrees from Mars and 5 degrees from Saturn.
  • August 4 — The moon appears 8.5 degrees to Saturn’s upper left.
  • August 5 — Tonight, the moon appears 7.5 degrees to the upper right of Antares, the brightest star in Scorpius.  While they are far apart, notice the brightness and color of the star and the planet.  Binoculars will help show the star colors.

Mars continues its rapid eastward motion compared to the background stars.

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On August 21, Mars passes 1.5 degrees to the lower left of Zubenelgenubi.  Saturn is nearly 4 degrees to the upper left of Mars.

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A few nights later, Mars passes Saturn.  The two planets are separated by about 3.5 degrees.

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The moon appears with the planets late in the month.  On August 30, the moon is about 9.5 degrees to the lower right of Saturn.  On the next evening moon is 3 degrees to the left of Saturn and 3 degrees to the upper right of Mars.

Morning Sky

Venus continues to dominate the morning skies.  During August , Venus rises closer to the sun.  On August 1, it rises about 2 hours before the sun, but by month’s end, 75 minutes before the sun.  It is moving toward superior conjunction in October and then moves into the morning sky.  For more about Venus as a morning star, see our posting.  The rising point of Venus along the eastern horizon continues to be north of sunrise.  Early in the month, Venus rises about 6 degrees north of the sunrise point.  By month’s end, the difference is 8 degrees.

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On August, Venus passes 7 degrees from Pollux.

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Its rapid orbital motion can be seen as it meets an imaginary line with Castor and Pollux on August 11.

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The month’s event is the close passing of Venus and Jupiter.  On the morning of August 18, the planets appear less than 1/3 degree apart.   While appearing close together, they are millions of miles apart.  So the solar system diagram below.  On the preceding and following mornings, the pair is separated by about 1 degree.  Unlike the slower moving Mars, Venus moves very rapidly against the background of stars, making many close groupings one day affairs.

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At the same time of the Venus-Jupiter conjunction, look higher in the sky for the moon.  It is nearly 4 degrees from Aldebaran.

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Venus continues its rapid eastward motion with the moon catching the planetary pair on the morning of August 23.  On this morning they are over 5 degrees apart.

The morning sky during August provides interesting planetary pairings as well as the lunar-muted Perseid meteor shower.

 Solar System

The planets visible without a telescope as seen from about the solar system for August 15, 2014

The planets visible without a telescope as seen from about the solar system for August 15, 2014

 

The chart above shows the planets visible without a telescope as seen from north of the solar system on August 15, 2014.  (Click the image to see it larger.)  Venus and Jupiter appear on the morning sky of our planet.  Mars, Saturn, and Mercury are in the evening sky.

July 2014 Skywatching

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During the early evening hours of July and August, an assembly of stars arches across the sky.  During the evening it slowly marches westward.  Even from dark skies, it appears as a cloudy ribbon of light stretching from south to north.  When your eyes are well-adjusted you can see brighter sections and apparent gaps.  Through binoculars the ribbon resolves into a celestial stream of stars, glowing clouds along with striking voids.  This is our celestial home, the Milky Way galaxy.  From within the celestial community, we see our sidereal neighbors and a glowing rim that holds the far-off cities and states of seemingly innumerable stars.

The time-lapse video above shows the slow westward dance of the Milky Way from our planet’s rotation.  Leave the bright lights of the cities and travel into the country on moonless evenings.

Earth

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Our planet reaches its farthest distance (aphelion) from the sun on July 3 at 7 p.m.  At this time we are 94.5 million miles from the sun.  The chart above shows the orbits of Venus, Earth, and Mars with the planets’ positions as they appear on July 3.  (Click the image to see it larger.)  Notice the shapes of the orbits.  Venus’ orbit is nearly a circle, less than 0.6% from perfection.  Planet Earth’s orbital shape is about 2% from the circular perfection.  Mars’ orbit is obviously not a circle as it is 9.3% from being a circle.

The sun’s distance from the sun varies throughout the year.  At the closest point (perihelion) on January, we were over 3 million miles closer to the sun.

Sun

As the annual distance variation, the first thought is that the seasons are caused by this effect, though our planet is farther away from the sun during the hottest time of the year in the northern hemisphere.  The season cycle is from our planet’s tilt.  The sun’s changing rising and setting points along the horizon combined with the lengthening and shortening of the daylight hours are the effects of this tilt.

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This chart shows the hours of daylight for July 2014 in the blue section of the chart. The red line shows the length of daylight throughout the year. Calculated from data from the U.S. Naval Observatory.

The daylight hours in mid-northern latitudes decreases  nearly 45 minutes during the month.  By July’s end early risers will notice the sun rises a little later than early in the month.  The chart above shows the changing daylight hours during July.

Moon

NASA Photo

NASA Photo

Phase Date/Time Moonrise Moonset
First Quarter 07/05/14 (6:59 a.m.) 1:23 p.m. 12:45 a.m. (07/06)
Full Moon 07/12/14 (6:25 a.m.) 7:35 p.m. (7/11) 5:47 a.m. (07/12)
Last Quarter 07/18/14 (9:08 p.m.) 12:11 a.m. (7/19) 2:00 p.m. (7/19)
New Moon 07/27/14 (5:42 p.m.) 5:32 a.m. 7:49 p.m.

Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

Evening Sky

Jupiter rapid fades into bright sunlight during the month moving behind the sun (conjunction) on July 24.  It appears in the morning sky next month with Venus.

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Saturn and Mars appear in the southern sky during the month as shown here on July 1.

Mars and Saturn appear in the southern sky during July.  Mars begins the month about 5.5 degrees to the upper right of Spica.  During the month, Mars eastward motion carries it past the star.

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The moon moves into the region early in the month.  On July 15, the First Quarter moon is less than a half degree (one full moon diameter) to the lower left of Mars while the planet is 4 degrees from Spica.

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A few  nights later, the moon moves appears about 1.7 degrees below Saturn.

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Mars passes within about 1 degrees of Spica on the evening of July 12.  The separation is slightly larger than about the size of two full moons.

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During the month, Mars moves quickly eastward compared to the starry background. The separation between Mars and Spica is easily observed. By month’s end they are about 9 degrees apart.

Morning Sky

Venus continues as a brilliant Morning Star.  It rises about 2 hours before the sun in the northeastern sky.  On July 11, Venus rises north of the sunrise position and continues rising north of sunrise until it disappears into bright sunlight in October.  Read more about Venus as a Morning Star.

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Venus and the waning crescent moon appear together in the predawn skies during twilight on July 24.  Find a clear horizon to view the pair.

Mercury appears in the eastern morning sky throughout most of the month.  This elusive planet appears during twilight and never in a dark sky.  On July 12 it reaches its greatest angular separation from the sun.

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The waning crescent moon may provide some assistance in locating Mercury.  During bright morning twilight on July 25, the moon appears about 5 degrees to the lower right of Mercury while Mercury is 9 degrees to the lower left of Venus.

Solar System

Solar System July 2014

The chart above shows the planets’ positions on July 15, 2014.  Mars and Saturn appear on the evening side of the sky with Mercury and Venus in the morning.  Jupiter is behind the sun as visible from earth.  Notice that it is on the noon line meaning that it is in the sky during the day and not visible in the bright sunlight.

 

Sky Watching June 2014

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Hours of daylight for Chicago, Illinois from U.S. Naval Observatory Data.

The daylight reaches its maximum this month.  On June 1, the sun is in the sky for 15 hours, 1 minute.  At the summer solstice on June 21, the sun is in the sky for 15 hours, 13 minutes.  The chart above shows the daylight hours (the blue bar) compared to the number of daylight hours throughout the year.  (Click the images in this posting to see them larger.)

Moon

NASA Photo

NASA Photo

 

Phase Date/Time Moonrise Moonset
First Quarter 06/05/14 (3:39 p.m.) 12:38 p.m. 1:14 a.m. (06/06)
Full Moon 06/12/14 (11:11 p.m.) 7:57 p.m. 4:57 a.m. (06/13)
Last Quarter 06/19/14 (1:39 p.m.) 12:27 a.m. 11:44 a.m.
New Moon 06/27/14 (3:08 a.m.) 4:58 a.m. 7:49 p.m.
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

 Evening Sky

Mercury rapidly leaves the western sky early in the month and disappears into the sun’s glare.  It passes between Earth and the sun on June 19 and rapidly moves into the morning sky.

Meanwhile three bright planets are well-placed for viewing.

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Jupiter appears low in the west-northwest, near Castor and Pollux.  This giant planet is gradually disappearing into the sun’s glare.  By month’s end it sets in the western sky during twilight.

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Mars  is about halfway up in the southern sky as the sky darkens.  On June 7, the moon appears about 3 degrees to the lower left of the Red Planet.  During the month Mars moves eastward compared to its starry background.  On June 1, Mars is  about 14 degrees to the right (west) of Spica.  By month’s end the pair is separated by 6 degrees.

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A few nights later, the moon appears near Saturn.  Their separation is about 5 degrees.  Note the reddish star Antares.  It is about the same color and brightness as Mars.  Do not confuse them.

Morning Sky

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Venus is the lone bright planet in the morning sky.  It appears in the eastern sky before sunrise.  At the beginning of the month, it rises about 1 hour, 40 minutes before sunrise.  By month’s end, it rises about 2 hours before sunrise.  Read our posting about Venus as a Morning Star.  On the morning of June 24, a waning crescent moon appears about 2 degrees from Venus.

June offers the longest daylight hours and opportunities to view the bright planets.

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