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.

The Moon and Venus, July 24, 2014

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The Moon and Venus make an attractive pairing this morning as seen from the Chicago area. (Click the image to see it larger.)

For more about the planets see:

Mars and Saturn Tonight, July 23, 2014

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Mars and Saturn shine from the southwestern sky this evening as seen from the Chicago area.  (Click the image to see it larger.)

On July 12, Mars passed Spica as it moved eastward compared to the starry background.  Watch it approach Saturn during the next few weeks.

Saturn is between the stars Zubenelgenubi and Zubeneschamali.  It slowly moves eastward compared to the celestial backdrop.

Each night the stars and planets move westward from our planet’s rotation, causing the day-night cycle.  The planets, though, move in their orbits around the sun.  They move eastward in their orbits and sometimes appear to move westward compared to the stars.  The movements of Mercury, Venus and Mars are quick and easily observed across several nights.  Each night notice Mars’ increasing separation with Spica and Mars catches the slower moving Saturn.

 

Venus and the Moon This Morning, July 23, 2014

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What’s that bright star near the moon this morning?  It’s Venus.  The image above shows the pair at 4:50 a.m. CDT as seen from the Chicago area.  (Click the image to see it larger.)  Notice the night portion of the moon is gently illuminated.  As see from the moon our planet is nearing its full phase.  The bright sunlight reflected from Earth falls on the night portion of the moon.  This effect is called “Earthshine.”  A similar glow appears when the moon is bright in our sky.  Sunlight reflected from the moon falls in the night portion to gently illuminate it.  Take a walk when the moon is nearly full, you’ll see your shadow from the bright moonlight.

Tomorrow morning the pair appears close together.

For more about the planets see:

Mars and Saturn Tonight, July 10, 2014

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Mars and Saturn shine from the southern skies this evening as seen in the image above.  (Click the image to see it larger.)  Mars is less than 2 degrees from Spica.  Mars passes closest to Spica on July 12.  Tonight they are about 2 degrees apart.  Mars will rapidly move away from Spica and travel eastward against the starry background.  By month’s end Mars and Spica are about 9 degrees apart.

Saturn is farther east between Zubenelgenubi and Zubeneschamali.  Tonight it is about 2.5 degrees from Zubenelgenubi.

See our planet outlook for this month.

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.

Jupiter and The Moon Tonight, May 31, 2014

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The waxing crescent moon and Jupiter appear near each other this evening in the west-northwestern sky as seen from the Chicago area.  (Click the image to see it larger.)

Notice the night portion of the moon is gently illuminated by sunlight reflected from our planet.  “Earthshine” is visible when moon is at the crescent phase.

Jupiter, Mars and Saturn Tonight, May 23, 2014

Three bright planets appear in the evening sky as seen from the Chicago area.  (Click the images to see them larger.)

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Bright Jupiter shines from the west-northwest from in front of the stars of Gemini, with its bright stars Castor and Pollux nearby.

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Mars and Saturn appear in the southern sky with the bright star Spica between them.

More about the planets this month.

For more about Mars’ appearance in the evening sky, see Mars’ Retrograde

May 2014 Skywatching

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Sun

May brings about a strong rebirth of plant and human activity in the mid-northern latitudes.  With the brutal winter of 2013-2014, plant emergence is slow at the time of this writing as it is about two weeks behind typical years.

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During the month, daylight increases by nearly one hour.  The chart above, made from data from data from the US Naval Observatory for Chicago, Illinois , shows the length of daylight throughout the year.  The blue region shows the daylight hours for May.  By month’s end daylight lasts 15 hours.

Moon

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(NASA photo)

Phase Date/Time Moonrise Moonset
First Quarter 05/06/14 (10:15 p.m.) 10:58 a.m. 12:45 a.m. (05/07)
Full Moon 05/14/14 (2:16 p.m.) 7:07 p.m. 5:18 a.m. (05/15)
Last Quarter 05/21/14 (7:59 a.m.) 12:15 a.m. 11:44 a.m.
New Moon 05/28/14 (1:40 p.m.) 4:27 a.m. 7:13 p.m.
Times are Central Daylight Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

Evening Sky

Four planets are visible during the evening hours this month:  Mercury, Jupiter, Mars and Saturn.

Mercury

This elusive planet makes its best evening appearance of this year during May.  Mercury is always difficult to locate because it appears either in the eastern morning sky before sunrise or western evening sky after sunset.  Even as its best as an evening planet, it sets as twilight ends.  Mercury is best seen at month’s end.

Mercury and Venus are best seen as morning planets in the autumn or evening planets in the spring.  The plane of the solar system, known as the ecliptic, makes steep angles with the horizon during spring evenings and autumn mornings.

During May, Mercury reaches its greatest angular separation from the sun, known as greatest elongation east.  The planet is east of the sun, making it visible in the western sky after sunset.

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Mercury’s orbit is tilted about 3 degrees compared to the ecliptic.  With Mercury reaching its greatest elongation and its greatest angle with the ecliptic, this coincidence provides the planet’s best evening appearance this year.

The chart above shows the ecliptic and Mercury’s orbit as the planet reaches its greatest angular separation from the sun.

 

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Even with favorable orbital factors, Mercury is difficult to see.  On the chart above, Mercury appears low in the western sky, just 30 minutes after sunset.  Bright Jupiter is nearly 23 degrees to the upper left of Mercury.

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On May 30, a thin waxing crescent moon appears about 8 degrees to the left of Mercury.

To locate Mercury, look with binoculars; after finding the planet, locate it without optical aid.

Jupiter

Jupiter is the bright “star” high in the western sky during the early evening hours.  It is in front of the stars of Gemini, with its bright stars Castor and Pollux.

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This giant planet is moving eastward compared to its starry background.  The chart above shows the planet’s motion during the month, indicating Jupiter’s position on May 1, 10, 20 and 30.  Weekly observations of the planet will reveal the motion of the planet.

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Early in the month, the moon moves through the region sky near Jupiter.  The best evening is May 4, when Jupiter and the moon are about 9 degrees apart.

Mars

Meanwhile Mars is well up in the southeastern sky at sunset.  It continues to move westward (retrograde) for most of the month, until May 21st.  It then resumes its eastward motion compared to the stars.  (See our posting about the retrograde motion of Mars.)

 

Saturn

Saturn reaches opposition on May 10 and enters the evening sky at sunset.  The planet is south at midnight, and it sets at sunrise.

At the beginning of the month, Mars and Saturn are 40 degrees apart.

To distinguish the planets from the stars, Jupiter is the brightest starlike object in the western sky.  It is twice the brightness of Mars.  Mars is over three times brighter than Saturn, making Jupiter nearly 7 times brighter than Saturn.

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Just before mid-month, the moon moves through the region of the sky with Mars and Saturn.  On May 10, the moon is 6 degrees to the right of Mars.  The next evening, the Moon is 9 degrees to the lower left of Mars.  On May 13, Saturn is 5 degrees to the lower left of the Moon.  On May 14, the pair is 9 degrees apart.

Morning Sky

Venus remains the brilliant “Morning Star” in the eastern sky before sunrise.  See our posting about Venus’ morning appearance.  Venus is low in the sky for the reasons explained with Mercury’s favorable view this month.

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The angle of the ecliptic is low, on spring mornings, and the planet is beneath the solar system plane.  The result is that Venus appears low in the sky.

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On May 25, the waning crescent moon appears 2 degrees from Venus.

Visible Solar System

sol_system_1405 The chart above shows the solar system from above on May 15, 2014.  (Click the image to see it larger.)  Notice that four planets — Mercury, Mars, Jupiter, and Saturn — appear in the evening sky.  Venus is the lone planet in the morning sky.

Happy sky watching!

 

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