Table of Contents

2018, August 13: Venus and Moon

August 13, 2018: The crescent moon and Venus.

The waxing crescent moon is 10 degrees to the right of Venus this evening. Tomorrow evening the moon appears above Venus.

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2018, August: The Evening Planet Parade Begins to Split

August opens with bright Mars in the sky nearly all night, setting about 45 minutes before sunrise.  It is just past its perihelic opposition and closest approach.  Watch Mars dim in brightness and diminish in size as our planet pulls away from its outer neighbor. Mars, the second brightest planet, shines 4° above the southeast horizon during early evening twilight. The other three bright planets – Venus, Jupiter, and Saturn – are farther west. Mercury still has an eastern (evening) elongation, but it sets only 8 minutes after the sun. This speedy planet is headed for its inferior conjunction early in the month.  At Nautical Twilight, 70 minutes after sunset, brilliant Venus, approaching its greatest elongation, is in the west between Regulus and Spica, 29° to Spica’s lower right.  Watch Venus close the gap with Spica during the month.  It is on a shorter and faster solar orbit.  Venus is slowly catching Earth in the same way Earth caught and passed Mars. (From Mars, Earth just passed what we call inferior conjunction for Earth’s inner planets.)  Jupiter is in the south-southwest in Libra, near Zubenelgenubi. Saturn, above the Teapot of Sagittarius, is in the south-southeast as the sky darkens. For the summer season the change of the length of daylight is noticeable during the month.  At the beginning of August, the sun is in the sky for 14 hours, 25 minutes.  With twilight, the dawn to dusk time is 18 hours, 13 minutes.  By month’s end daylight is reduced to 13 hours, 10 minutes and 16 hours, 38 minutes with the three phases of twilight.  Here are the highlights for the beginning of the month:

  • August 1: It’s Perseid Meteor Shower showtime!  The shower’s peak display occurs during the moon’s New phase this year.  The meteors appear to emerge from a point in space (radiant), much like the effect of falling snowflakes when you drive through a snowstorm.  During the shower period, Perseids can be seen anywhere in the sky, at any time of the night.  Some meteors are flashes that catch your eye, while others are brighter, leaving a train that persists for a short time.  Trace the path of the meteor backward toward Perseus to determine whether it’s a Perseid or a sporadic meteor (not associated with the shower). When reversing the track, the random meteor’s origin is in another part of the sky.  The highest meteor counts occur as the radiant approaches the zenith after midnight and before the beginning of morning twilight.    To get a maximum meteor count, watch in a group of five observers, four looking above each cardinal point and one looking toward the zenith.  Cut the official estimates in half if you’re observing in or near town, because many of the meteors are dim; yet, others are bright and impressive to see.  Divide the predicted rate by 5, if you’re observing alone.  It is important to note that the predicted rates for all meteors visible are across the entire sky, not visible to an individual observer.  After midnight on the peak mornings, we see the meteoroids’ orbits nearly head on. So, at prime times, lone observers may see 10 meteors per hour in a dark location, 5 per hour in town.  This evening, Venus sets at Astronomical Twilight (sun’s altitude is −18°), 150 minutes after sunset.  For the remainder of the apparition, Venus sets during twilight.
  • August 4: The moon is at its Last Quarter phase, 1:18 p.m. CDT.
The moon in the morning sky, August 6, 2018

August 6: The waning crescent moon appears near the Hyades star cluster in the eastern sky before the beginning of morning twilight. Use binoculars to explore the star clusters near the moon.

  • August 6: In the morning near the time of Astronomical Twilight, about 2 hours before sunrise, the waning crescent moon is 5.1° from Aldebaran. The star is 28° up in the eastern sky.  The moon is 1.2° above Gamma Tauri, in the Hyades star cluster. Take in the view of the moon and star cluster with binoculars. In the evening sky, Jupiter is 90° east of the sun.  One hour after sunset, it’s 23° up in the southwest, about 1° to the upper right of Zubenelgenubi.
  • August 7: Have you looked for Perseids? If you wait long enough, you’ll see a few.
  • August 8: At 2 hours before sunrise, the waning crescent moon is 13° up in the east-northeast. While not in the best observing location, use binoculars to note that the moon is 4.6° to the lower left of the star cluster M35.  Mercury is at its inferior conjunction, 9:06 p.m. CDT.
  • August 9: Start looking for Sirius about 45 minutes before sunrise for its first appearance in your morning sky before sunrise, its helical rising date.  You’ll need a clear southeast horizon as Sirius appears only about 4° above the horizon at this first appearance.  “Dog Days” may be associated with the helical rising of Sirius.  It is coincidence is this occurs during the hot, humid days of August.
  • August 10: While the moon is near its new phase, visit a remote location, even for a short visit, to see the Milky Way arching across the sky from north to south.  Look for the bright nebulae and star clusters in the southern region in Sagittarius and surrounding regions, the Sagittarius Star Cloud, and the Scutum Star Cloud.  Be sure to check out the dust clouds of the Great Rift, nearly overhead in Cygnus and follow it southward as it breaks the glow of the Milky Way into two parts.  Some of my favorite August targets are the Ring Nebula, Epsilon Lyrae, Albireo, mainly because the double stars are celestial gems to show to new observers. Albireo’s contrasting star colors always impress beginning sky watchers. With binoculars, look for the “Double Cluster” h Persei and χ Persei.
  • August 11: The moon is at its New phase at 4:58 a.m. CDT. There is a partial solar eclipse visible from north and eastern Europe, northern parts of North America, and northern and western parts of Asia.
  • August 12: Look for Perseids after midnight and before morning twilight begins.
  • August 13: This year’s peak Perseid rate may occur this morning according to NASA’s meteor expert Bill Cooke, cited in a space.com article (https://tinyurl.com/yb7ww7lh).
The waxing crescent moon appears above Venus and near the star Gamma Virginis in the early evening sky. Venus and Spica are 16° apart.

August 14: The waxing crescent moon appears above Venus and near the star Gamma Virginis in the early evening sky. Venus and Spica are 16° apart.

 

  • August 14: At mid-twilight (75 minutes after sunset, sun’s altitude is -9°), Venus is 4° up in the west. The waxing crescent moon is 6.6° to the upper left of Venus.  Gamma Virginis is about 2° to the lower right of the moon, and nearly 5° to the upper left of Venus.  Spica is 16° to the upper left of Venus.
  • August 15: At mid-twilight (60 minutes after sunset), Spica is 9° up in the west-southwest, with the waxing crescent moon (4.7 d, 27%) 6.5° above the star. The Venus-Spica gap is 15°.

 

At mid-month at evening Nautical Twilight (75 minutes after sunset), the four bright planets span the sky from east to west, ranging from Mars in the southeast, Saturn in the south, Jupiter in the southwest, and Venus low in the west.  Venus is near its greatest elongation.  Watch Venus close the gap with Spica for a widely-spaced conjunction at month’s end.  In the morning dim Mercury, only 11° west of the sun, is moving toward a favorable morning greatest elongation at month’s end.  Now, though, it is quite dim, but watch it brighten about 30 times during the next two weeks.  Continue to look for Perseid meteors.  Here’s what’s up during the second half of the month:

Jupiter passes Zubenelgenubi for the third conjunction during this appearance of the giant planet. The waxing crescent moon is nearby.

August 16: Jupiter passes Zubenelgenubi for the third conjunction during this appearance of the giant planet. The waxing crescent moon is nearby.

  • August 16: Jupiter, 18° up in the southwest at mid-twilight (50 minutes after sunset), passes 0.5° from Zubenelgenubi. This is the third conjunction during Jupiter’s apparition.  The waxing crescent moon is 7° to the right of Jupiter.
  • August 17: Venus reaches its greatest elongation (45.9°), 70 days before its inferior conjunction.  The thick waxing crescent moon  is 6.6° to the upper left of Jupiter.  Slow-moving Jupiter remains close to Zubenelgenubi, 0.6° this evening.  Watch the gap widen during the next several weeks as Jupiter creeps eastward.
  • August 18: The moon is at its First Quarter phase, 2:49 a.m. CDT.
  • August 19: At mid-twilight, Antares stands 18° up in the south-southwest with the waxing gibbous moon 10° to the upper left of the star and 16° to the right of Saturn.
  • August 20: The Venus-Spica gap is 10°. Venus is 32° to the lower right of Jupiter. This evening, the waxing gibbous moon is 3.9° to the right of Saturn.
August 20: In the early evening sky, Venus and Spica are 10° apart. Venus is 32° to the lower right of Jupiter.

August 20: In the early evening sky, Venus and Spica are 10° apart. Venus is 32° to the lower right of Jupiter.

  • August 21: This evening, the waxing gibbous moon is 8.1° to the left of Saturn, 25° up in the south during mid-twilight.
  • August 22: The moon (11.7 d, 90%) is 8.8° to the upper right of Mars.
  • August 23: At 30 minutes before sunrise, Mercury, 8° up in the east-northeast, 21° below Pollux and 22° to the lower left of Procyon. During the next two weeks, look for Mercury far below Pollux. The gap between them grows about 0.5° each day. Have you looked for Sirius during morning twilight?  In the evening sky, the moon is 8° to the upper left of Mars.
  • August 24: What is the last date that you see a Perseid meteor?
  • August 26: Mercury is at its morning greatest elongation. The separation from the sun is only 18.3°, but the ecliptic has a 25-degree inclination, favorable for locating Mercury.  Mercury rises 90 minutes before sunrise in the east-northeast. Look for it with binoculars 23° below Pollux. The moon is Full at 6:56 a.m. CDT.  In the evening sky the Venus-Spica gap is 5°.
August 27: Mars’ retrograde ends near the asterism Dog’s Country, a kite-shape group in Sagittarius. Look with binoculars when the sky gets dark.

August 27: Mars’ retrograde ends near the asterism Dog’s Country, a kite-shape group in Sagittarius. Look with binoculars when the sky gets dark.

  • August 27: Mars’retrograde ends this evening near the kite-shaped asterism Dog’s Country. The group made of Omega Sagittarii, 59 Sagittarii, 60 Sagittarii, and 62 Sagittarii.  Tonight, Mars is 2.6° from Omega Sagittarii.
August 31: A Venus-Spica Conjunction. Venus appears 1.2° below Spica.

August 31: A Venus-Spica Conjunction. Venus appears 1.2° below Spica.

 

  • August 31: Venus passes 1.2° below Spica. After this conjunction, Venus sets much earlier each evening, nearly mirroring the setting time of Spica. They disappear into bright twilight together, not setting more than about 15 minutes apart as they head toward their respective solar conjunctions.  This evening Venus is 24° to the lower left of Jupiter.

As the month ends, the summer planet parade begins to lose its brightest planet.  Now setting 85 minutes after sunset, Venus is heading toward its phase of greatest brightness.  Through a telescope, Venus displays a thick evening crescent phase that is 29.5” across.  With Venus near Spica, the pair begins to descend into evening twilight.  Speedy Mercury, now fading from the morning sky, is moving toward its superior conjunction late in September.  Jupiter, visible in the southwest in Libra east of Zubenelgenubi, appears to be heading toward an evening conjunction with Venus.  Watch what occurs next month.  Saturn, slowest moving among the other brighter planets in the planet parade, begins the evening in the south.  Spectacular Mars, shining in the sky nearly all night, starts the evening in the south-southeast.  The moon rises in the east around 10:30 p.m.  When did you first see Sirius in the pre-sunrise sky?  How many Perseids did you see? Did you check your star charts to determine the Perseids’ radiant location? Did you observe the Milky Way?

2018, July 9: Venus Passes Regulus

Brilliant Venus passes about 1 degree from Regulus this evening.  Watch as it now pulls away from this star and heads toward Spica.  That conjunction is at the end of August.

Click here for the blog’s table of contents

Look for 5 planets during the month.  From mid-northern latitudes, they are not visible simultaneously.  Look for Mercury about 30 minutes after sunset with binoculars, then wait for Mars to cross the southeastern horizon.  Four bright planets then span the sky from Mars to Venus.  Mars reaches its opposition later in the month.  The planet is closer than it’s been since 2003.

2018, July 6: Jupiter and Saturn in the Southern Sky

While Venus shines in the western sky, Jupiter and Saturn appear in the southern sky with Antares between them. The star is the brightest star in Scorpius.

Bright Jupiter, in the south-southwest, appears to the upper right of Zubenelgenubi.  Watch Jupiter approach and pass the star during the next month.

Saturn, just past its opposition, shines in the southeast, is 52 degrees to the lower ft of Jupiter.

Click here for the blog’s table of contents

Look for 5 planets during the month.  From mid-northern latitudes, they are not visible simultaneously.  Look for Mercury about 30 minutes after sunset with binoculars, then wait for Mars to cross the southeastern horizon.  Four bright planets then span the sky from Mars to Venus.  Mars reaches its opposition later in the month.  The planet is closer than it’s been since 2003.

2018, July 6: Venus Closes in on Regulus

Brilliant Venus shines from the western sky during twilight this evening. It appears about 3.5 degrees from the star Regulus that is the brightest star in Leo the Lion.

Venus passes the star on the evening of July 9.

Click here for the blog’s table of contents

Look for 5 planets during the month.  From mid-northern latitudes, they are not visible simultaneously.  Look for Mercury about 30 minutes after sunset with binoculars, then wait for Mars to cross the southeastern horizon.  Four bright planets then span the sky from Mars to Venus.  Mars reaches its opposition later in the month.  The planet is closer than it’s been since 2003.

2018, July: See Five Planets and Mars Opposition

Click here for the blog’s table of contents

Look for 5 planets during the month.  From mid-northern latitudes, they are not visible simultaneously.  Look for Mercury about 30 minutes after sunset with binoculars, then wait for Mars to cross the southeastern horizon.  Four bright planets then span the sky from Mars to Venus.  Mars reaches its opposition later in the month.  The planet is closer than it’s been since 2003.

July opens with the waning gibbous moon in the south-southwest. Mars, now the second brightest planet, is 25° up in the south-southwest, 5.8° below the moon.  At the same time, Saturn is 10° up in the southwest.  With both planets near their oppositions, they appear in the southeastern sky during the evening and move westward during the night.  During the early evening, four bright planets are arched across the sky, with the trio of bright outer planets in retrograde.

One hour after sunset, brilliant Venus stands 14° up in the west.  Venus is 9° to the lower right of Regulus.  Watch Venus close in and pass Regulus during the first 9 days of the month.  At this hour, dimmer Mercury is 4° up in the west-northwest, setting nearly 90 minutes after sunset. Use binoculars to locate it. This speedy world approaches its greatest elongation during the first half of the month.

Meanwhile, bright Jupiter, 82° to the upper left of Venus, is 33° up in the south.  This giant planet is 2° west of Zubenelgenubi.  Saturn, just past its opposition and retrograding above the Teapot of Sagittarius, is 13° up in the southeast, 52° to the lower left of Jupiter.

Mars, racing toward its opposition later in the month, rises in the southeast 117 minutes after sunset.  The Red Planet, retrograding in Capricornus, appears 34° to the lower left of Saturn.  Start looking for the five naked eye planets during the early evening.  Look for Mercury during twilight, then wait for Mars to clear the southeast horizon. Here are the highlights for the first half of the month:

  • July 1: As the sky darkens, Venus is 9° to the lower right of Regulus.  Mars rises 117 minutes after sunset this evening.  The waning gibbous moon is 15° to the left of the planet.

  • July 2: The Venus-Mercury gap is 16.6°. Mercury sets 90 minutes after sunset, its maximum setting interval after sunset for this apparition. The Venus-Regulus gap is 8° this evening.  Watch Venus close the separation during the next several evenings: 07/03, 6.9°; 07/04, 5.7°; 07/05, 4.7°; 07/06, 3.6°; 07/07, 2.6°; 07/08, 1.5°.
  • July 4: The Venus-Mercury gap is 16.2°.  Mercury’s brightness is fading fast as it approaches its greatest elongation.  This evening its apparent magnitude is 0.2, but it is appearing in bright twilight.
  • July 6: The moon is at its Last Quarter phase at 2:51 a.m. CDT. Earth is at aphelion 94.5 million miles from the sun at 11:46 a.m. CDT.

    In early July, Venus passes the next signpost of the ecliptic, Regulus. This vivid blue star is less than one degree from Venus on July 9.

     

  • July 9: Venus is closest to Regulus this evening, 1 degree.  The planet appears to the upper right of the star.  Watch the gap widen during the next several evenings as Venus moves away and toward Spica. Venus has a conjunction with Regulus in about 13 months when they are near their solar conjunctions, both hiding in bright sunlight.  On October 3, 2020, Venus, 22° up in the morning sky at 90 minutes before sunrise, appears 33’ below the star.  On the previous morning, Venus is 36’ above Regulus.
  • July 12: Mercury is at its greatest elongation, 26.4° east of the sun at 12:29 a.m. CDT. Mercury is only 13° above the horizon at sunset. The Venus-Mercury gap is 16.4°.  Venus is now 3.4° past Regulus.  The gap grows about 1° each evening.  The moon is at its New phase, 9:48 p.m. CDT.
  • July 14: Not long after sunset look for the waxing crescent moon 2.1° to the left of Mercury with binoculars.  Mars passes 1.1° north of Psi Capricorni.
  • July 15: Venus passes 1° to the upper right of Rho Leonis.  The waxing crescent moon is between Venus and Regulus, 1.5° to the lower right of Venus and 5.1° to the upper left of Regulus.

At mid-month, Venus continues to dominate the evening sky with its brilliance.  At 65 minutes after sunset, Venus is 11° up in the west, setting about an hour later.  Venus is now 6.5° to the upper left of Regulus.  On July 15, the waxing crescent moon is 1.5° to the lower right of Venus. Mercury, now past greatest elongation and fading quickly into the sun’s glare, sets 71 minutes after sunset.  Use binoculars to catch it in bright twilight.  Jupiter, near Zubenelgenubi, is 30° up in the south-southwest.  Saturn, 19° up in the south-southeast, is 51° to the lower left of Jupiter.  Mars, the second brightest “star” and rising 65 minutes after sunset, is approaching its perihelic opposition. It is 18° up in the southwest 2 hours before sunrise.  Here are the highlights for the second half of the month:

July 16:  The waxing crescent moon is 11.9° to the upper left of Venus.  The Venus-Regulus gap is 7.7° and growing each day.

  • July 17: Jupiter’s retrograde ends 2° west of Zubenelgenubi.  Watch Jupiter move eastward toward the star during the next month. The waxing crescent moon is 24.8° to the upper left of Venus.  If you’ve not looked for all five naked eye planets, start looking for Mercury, 30 minutes after sunset with binoculars.
  • July 18: The waxing crescent moon is 9.2° to the upper right of Spica. During the next several nights, start looking for some Perseid meteors before the moon approaches its full phase, after midnight, and before morning twilight begins.
  • July 19: The moon is at its First Quarter phase, 2:52 p.m. CDT.  This evening the moon is 13.3° to the right of Jupiter.
  • July 20: Today is the 49th anniversary of Apollo 11’s historic moon landing. This date also marks the 42nd anniversary of the Viking 1 landing on Mars.  The waxing gibbous moon is 3.5° above Jupiter this evening.
  • July 22: The waxing gibbous moon is 8.4° above Antares.
  • July 24: This evening the waxing gibbous moon is 1.9° to the upper right of Saturn.

  • July 27: Mars (m=-2.8) is at opposition.  The Full Moon is 7° to the upper left of Mars.  The moon reaches its Full phase, 3:20 p.m. CDT.  Mercury (m=1.9) 32 minutes after sunset during early twilight.
  • July 31: Earth and Mars are closest (closest approach), 35.7 million miles away.

The month ends with four bright planets lined up across the early evening sky.  Brilliant Venus is 9° up in the west 70 minutes after sunset.  Mars is 7° up in the southeast.  Mars retrogrades until August 27.  It is 30° to the lower left of Saturn, 23° up in the south-southeast, above the Teapot of Sagittarius.  It retrogrades until September 6.  This ringed wonder is 49° to the left of Jupiter.  Jupiter is 26° up in the southwest, 1.5° to the right of Zubenelgenubi.  Watch this giant world narrow the gap to the star and pass it next month.  Jupiter is 50° to the left of Venus.

2018, June 1: #Mars Observations

From Astronomy Picture of the Day

From Robert C. Victor

Jeff,

This is dated material. Some of the events happen this week. Please share with others who may be interested. Thank you!

Skywatchers in midwestern U.S.,

On most of the last several mornings, I have taken my 6-inch Orion Dobsonian reflector outdoors during the couple of hours before sunrise, and used a 6-mm eyepiece (providing a magnification of 200-power) to observe Mars and Saturn. The south polar cap of Mars was immediately obvious!

The Martian southern hemisphere spring equinox occurred on May 22, so the polar cap is still near its maximum extent. I also noticed some dark markings on the disk, near the equator and southern latitudes, and a bright area near the following or morning (celestial east, Martian west) limb, which may have been morning frost or morning clouds. And at the northern limb, I noticed a very narrow bright area that could have been the edge of the northern polar hood of clouds. The north pole itself is tipped away from Earth by 15 degrees.

Keep in mind that as spring progresses in the Martian southern hemisphere, the southern polar cap will shrink rapidly, so if you wait until Mars becomes conveniently visible in the evening, a much smaller polar cap will remain. Opposition and closest approach of Mars will occur in the last week of July, but don’t wait until then!

In coming days, two of the most striking markings on Mars (in addition to the South Polar Cap) will be in excellent position as seen from the eastern U.S. in the hours before dawn, when Mars is highest in the southern sky.

The markings are (1) Syrtis Major, which displays a dark triangular shape resembling a northward-pointing India, centered just north of the Martian equator. Also at the same Martian longitude (290 degrees) is (2) Hellas Basin, which often appears very bright because of haze or surface frost deposit. Hellas is centered near lat. 42 degrees south and so appears between Syrtis Major and the South Polar Cap.

Currently, any particular Martian surface feature reaches the central meridian of Mars a little over 38 minutes later each day. So if you observe Mars at the same time each morning, a feature will first appear near the sunset terminator, near the celestial west limb of Mars where the solar illumination cuts off. (You’ll notice in early June that Mars appears not round, but in gibbous phase.) Each successive day at the same time, the Martian feature will move farther back from the sunset terminator, eventually passing near the center of the disk, and continuing on toward the morning (celestial western) limb. In each 24 hours, Mars makes less than one complete rotation.

Here are times (in CDT) when the longitude of the central meridian of Mars is equal to 290 degrees. At these times, Syrtis Major will appear a little north of the center of the Martian disk, and Hellas will appear well south of the disk center. Even if you observe up to three hours away from these times, the east-west foreshortening of these features will be less than 50 percent, but you’ll not want to observe too many hours before Mars reaches your local meridian — it’ll be too low for good seeing — or much after Mars crosses your local meridian, because you’d be viewing in the daytime.

Longitude of central meridian of Mars = 290 degrees;
Syrtis Major and Hellas transiting central meridian.

Tuesday      June  5   2:26 a.m. CDT
Wednesday June  6   3:04 a.m.
Thursday     June  7   3:43 a.m
Friday          June  8   4:21 a.m.
Saturday      June  9   4:59 a.m.
Sunday       June 10   5:38 a.m. (near sunrise, but observe earlier,
as these features approach the central meridian)

Monday    June 11   6:16 a.m.  ” ”
Tuesday   June 12   6:54 a.m.  ” ”

RCV