2017, February 12: The Winter Sky

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The Winter Stars gleam brightly from the southern sky this evening.  Orion, with its bright stars, Betelgeuse and Rigel, slowly march westward.  Within the constellation is the Orion Nebula that appears as a fuzzy cloud through a small telescope or binoculars.  Aldebaran appears in front of the Hyades star cluster, that appears in a check mark shape or a letter “V” if you include the bright star.  The Pleiades star cluster is to the upper right of the Aldebaran.  You can count six or seven stars.  Through binoculars you may see a few dozen.

The clear winter sky tonight provides for excellent sky watching.

2016, November 3: Venus, Saturn, Moon & Mars

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Brilliant Venus shines from the western sky this evening as seen from the Chicago area.  The moon, overexposed in the image, appears about 10 degrees to the upper left of Venus.  Dimmer Saturn is 6 degrees to the right of Venus.  The red planet Mars is 36 degrees to the upper left of Venus.  During the month, watch Venus get closer to Mars.  For more about the planets see the articles linked above.

2017: The Mars-Venus Encounter

This appearance of Venus and Mars has concluded.

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Update:  Here are the planets when they were closest on February 3.

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A Recent Venus-Mars Conjunction

On an interval that varies from several days to nearly 23 months, Venus and Mars can appear very close together in the sky.  These conjunctions can be very close (Epoch) or with very wide separations.  During the conjunction displayed in the above image (November 3, 2015), the planets appeared about 0.7 degree (42 minutes) apart.  On October 5, 2017, they appear over 3 times closer with a separation of .22 degree (13.2 minutes).  (In the sky we measure the separation of objects by a geometric angle as seen from Earth.  The full moon’s diameter is about 0.5 degree. Your little finger at arm’s length covers a full moon.  Try it during the next time the moon is full. In the above image Venus and Jupiter are separated by about 7 degrees.  Your fist at arm’s length covers about 10 degrees in the sky.)

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At its brightest, Mars shines as the third brightest starlike object in the sky, following Venus and Jupiter.  This occurs when Mars is at opposition, when it is closest to Earth and opposite the sun in the sky.  At opposition, Mars rises in the east at sunset, appears in the south at midnight and sets in the west at sunrise.  Conjunctions of Mars (and the planets beyond Earth) with Venus occur when Venus is within 47 degrees of the sun.  This angle is the greatest angular separation that Venus has from the sun from our home planet view.  Yet, if Venus and Mars appear too close to the sun, they are lost in the sun’s brightness and not visible from Earth.  Because Mars is far from our planet during a Venus conjunction, it is not near its maximum brightness, so Venus always appears very bright in the sky and a conjunction with Mars occurs when the Red Planet is dimmer. A Venus-Mars conjunction does not occur when Mars is near its brightest (at opposition)  Notice Mars’ brightness in the image at the beginning of this article from the 2015 conjunction.

Notice that Venus does not appear at opposition; so it is not visible at midnight.

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At the time of this writing, Venus has recently entered the evening sky and passed its Epoch Conjunction with Jupiter.  On September 15,2016, Venus appears low in the sky in the west.  Saturn and the star Antares are farther south.  Mars is beyond them, about 62 degrees from Venus.

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From a view outside the solar system, this 62-degree angle is represented in the chart above.  In all these charts, Earth is at the geometric vertex of the angle.

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As the dates advance toward the New Year, Venus moves closer to Mars.  The chart above shows the setting times of planets, the moon, and selected stars compared to sunset during part of 2017, until Mars disappears into the sun’s glare.  On January 1, 2017, notice on the chart that The moon sets close to the time of the setting of Venus (14 minutes difference).  This indicates that they appear close to each other in the sky.  Mars follows Venus by about an hour.

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This chart represents what we see in the sky during the early evening on New Years Day.  Venus and the Moon are 4 degrees apart with Mars about 12 degrees to the upper left of Venus.

During January 2017, Venus and Mars appear to move closer together as the setting lines of the two planets begin to converge.

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On February 3, 2017, the planets close to 5.5 degrees, with Mars setting 19 minutes after Venus.  The chart above shows their close angular proximity, but they are nearly 126 million miles apart in space, over 300 times the distance between the earth and the moon.

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In the sky, brilliant Venus dominates the southwestern sky with dimmer Mars 5.5 degrees to its upper left.

After this near meeting, Venus rapidly moves back toward the sun, as indicated by the rapidly decreasing time it sets after the sun as indicated by the setting graph earlier in this article.  The planets appear farther apart on the sky as the time difference in their settings increases.

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On March 1, the planets are 13 degrees apart with the moon 5 degrees to the lower left of Mars.

By March 15, Venus sets at the beginning of twilight and 4 days later it sets in bright twilight.  This is a rapid plunge into the sun’s glare.

On March 25, Venus passes between the earth and sun (inferior conjunction) and rapidly moves into the morning sky.  Mars slowly sets earlier each night until it disappears into the sun’s glare toward its solar conjunction on July 27.

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In late April, Mars moves through Taurus, which has two prominent star clusters:  Pleiades and Hyades.  The Pleiades star cluster is a compact cluster of many blue stars.  Commonly named the “Seven Sisters,” the cluster is a spectacular sight through binoculars.  Mars passes closest to the cluster (3.5 degrees) on April 21.    With binoculars the cluster and the planet are be visible at the same time.

The bright star Aldebaran appears in line with the Hyades cluster; its loosely collected stars resemble a check mark.  The Hyades cluster is another spectacular view through binoculars.

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On April 28, the moon joins the view in the western sky when it is 4 degrees to the upper left of Aldebaran.  Mars continues its planetary motion among  these stars.

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On April 29, Mars and Aldebaran set at the same time, but they are nearly 7.5 degrees apart.  By this date, Venus is shining brightly in the morning sky rising about 90 minutes before sunrise.

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On May 6, Mars passes 6.5 degrees to the upper right of Aldebaran.  A few days later, Mars begins setting during evening twilight, each night setting deeper into the glow after sunset;  It moves behind the sun on July 27.

Upcoming Venus-Mars Conjunctions

  • October 5, 2017 — 13.2 minutes separation
  • August 24, 2019 — 18.6 minutes
  • July 3, 2021 — 29.4 minutes

 

Our images and charts collections are available here –> http://goo.gl/Sfp1ur

See our article about Venus’ evening appearance.

See our  article outlining the planets in the evening sky in 2016.

Venus & Jupiter, April 2015

Venus and Jupiter gleam from the evening sky during April 2015.  Venus is the bright celestial gem that sparkles in the western sky after sunset.  It sets over three hours after the sun, making it easily observed.  The difference between sunset and the planet setting grows to nearly 3 hours, 40 minutes after sunset by months end, allowing Venus to around midnight.

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Early in the month, Venus appears nearly 19 degrees to the upper left Mars, fading in brightness and moving into the sun’s bright glare. As the month progresses, Venus moves higher in the sky as the stars appear lower in the west each night at the same time.  Watch Venus approach and move between the Pleiades star cluster and the star Aldebaran near mid-month.  Early in the month. Venus is about 10 degrees below the Pleiades and 20 degrees to the lower right of Aldebaran.

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Meanwhile, Jupiter, shines from the southeastern sky near the star Regulus, 80 degrees from Venus.  By late June, Jupiter and Venus appear very close together in the western sky just after sunset.

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During the second week of the month, Venus passes the Pleiades.  On the evenings of April 10 and April 11, Venus appears about 2.5 degrees to the left of the cluster.  Look through binoculars to capture a captivating view of the brilliant planet and the star cluster.

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Venus appears to move between the Pleiades and Aldebaran on April 13, with the star about 10 degrees from Venus.

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Late in the month, the moon joins the grouping.  On April 20 the moon appears to the lower left of the Pleiades.  On April 21, the moon appears about 4 degrees to the upper left of Aldebaran.

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The moon moves farther east each night and reaches Jupiter on April 26, appearing nearly 8 degrees from this giant planet.

By month’s end Venus and Jupiter at about 50  degrees apart and two months from a spectacular conjunction in the western sky.

January 2015 Sky Watching

 Sun

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Days continue to lengthen after the December solstice.  The shaded area of the chart above (click it to see it larger) shows the amount of daylight in January compare to the entire year, the red curve.  Daylight increases by nearly 50 minutes during January; by month’s end the sun is in the sky for 10 hours.  (The chart is calculated from U.S. Naval Observatory data)

Earth at Perihelion

The Earth reaches its closest point to the sun on January 4 at 1  a.m. in its slightly eccentric solar orbit.  The perihelion distance is about 3% closer to the sun than it is at its farthest point (aphelion) on July 6.

Moon Phases

NASA Photo

NASA Photo

Phase Date/Time Moonrise Moonset
Full Moon 01/04/15 (10:53 p.m.) 4:34 p.m. 7:14 a.m. (01/05)
Last Quarter 01/13/15 (3:46 a.m.) 12:08 a.m. 11:26 a.m.
New Moon 01/20/15 (7:14 a.m.) 6:55 a.m. 5:28 p.m.
First Quarter 01/27/15 (10:48 a.m.) 11:24 a.m. 1:38 p.m. (01/28)
Times are Central Standard Time for Chicago, Illinois, from US Naval Observatory calculations. (For mjb)

Evening Sky

Four bright planets appear in the evening sky during January.  Mercury, Venus, and Mars appear in the southwestern sky during evening twilight.

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Early in the month Mercury appears near Venus.  When visible, Mercury appears near the horizon and only during twilight.  From Earth, it is never seen in a dark sky.  Venus and Mercury are emerging out of the sun’s glare.  Use Venus to locate Mercury  on days around January 10.  The chart above shows the pair on January when they are less than one-half degree apart with Mars about 20 degrees to the upper left of them.

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Late in the month, the moon passes the western sky planets.  On January 21, it appears with Venus and Mercury, with the two planets separated by about 9 degrees with Mars about 13 degrees to the upper left of the trio.  On January 22, the moon 4 degrees to the right of Mars.  On the next evening the moon is 12 degrees to the upper left of the Red Planet.

Meanwhile, Jupiter rises in the east around 8 p.m. early in the month,

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Jupiter shines from in front of the stars of Leo with its bright star Regulus.  The head of the lion figure in the stars resembles a backwards question mark and is commonly known as “The Sickle.”  The chart above shows Jupiter and Leo on January 10, when Jupiter and Regulus are 9 degrees apart.

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On the night of January 7/8, the moon appears  near Jupiter and Regulus.  The chart above shows them at 2 .m. (January 8) when they appear in the southern sky,

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During the night, Jupiter appears to move westward, as our planet rotates.  The chart above shows Jupiter and Leo high in the western sky at 4 a.m. on January 15.

 Morning Sky

As Jupiter shines from the western sky  in the mornings of January, Saturn climbs into the southeastern sky.

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This Ringed Wonder shines from in front of the stars of Scorpius, with its bright star Antares.  On January 8, appears about 10 degrees above the star.

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On January 16, the crescent moon appears near Saturn.

Comet

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Comet Lovejoy brightens during the evenings of January.  While comets rarely “burn bright,” this one is brighter than most.  Some observers have reported seeing the comet without optical assistance after they first found it with binoculars.  The chart above shows the comet on the evening of January 15 when it is near Aldebaran and the Pleiades.  Look for it with binoculars.  It appears as a fuzzy mass with a concentrated center.  A fuzzy tail may extend to the east.  Once found with binoculars, look for it with your eyes alone without the help of the binoculars.

Jupiter Tonight, April 7, 2013

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Bright Jupiter gleams from the western sky at 8:25 p.m. CDT this evening as seen from the Chicago area in this 15-second exposure. (Click the image to see it larger.)  This Giant Planet shines in front of the stars of Taurus with its brightest star Aldebaran.  Two bright star clusters, Pleiades and Hyades, shine nearby.  They are best viewed through binoculars.  Zeta Tauri and Elnath mark the horns of the bull.  Betelgeuse (Orion) and Capella (Auriga) also appear in the view.

For more about the April sky, see our monthly skywatching description.

Skywatching April 2013


Image Source

Daylight continues to increase throughout April.  Nearly 80 minutes of daylight are added during the month as the sun rises north of east, rises higher in the south and sets north of west this month.

Moon Phases

Moon Phase Date Moonrise Moonset
Last Quarter April 2 1:39 a.m. 12:33 p.m.
New Moon April 10 5:59 a.m. 8:49 p.m.
First Quarter April 18 12:16 p.m. 2:25 a.m. (4/19)
Full Moon April 25 7:56 p.m. 6:20 a.m. (4/26)

Data from US Naval Observatory

The Evening Sky

Jupiter continues to dominate the sky throughout the month.  On April 1, this giant planet is about halfway up in the western sky at sunset.  It appears lower in the west each week at the same time.

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On April 14, the waxing crescent moon appears about 4 degrees to the left of Jupiter.  The chart above shows the grouping at 8:30 p.m. CDT.  The moon and Jupiter appear in front of the stars of Taurus with its bright star Aldebaran and prominent Pleiades star cluster.

Saturn rises into the eastern sky shortly after sunset this month.

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On April 28, Earth moves between Saturn and the sun as shown in the diagram above.  (Click the chart to see it larger.)  At this time, Saturn is visible in the sky all night and it is closest to Earth as it gets.  At opposition, Saturn rises in the southeast at sunset.  During the evening hours it rises higher into the sky, appearing south at midnight.  During the early morning hours, it moves westward appearing lower in the southwest as it sets at sunrise.

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A few days before opposition, the moon appears near Saturn.  The chart above shows the moon’s eastward movement at 10 p.m.  CDT each evening.  On April 24, the bright nearly full moon is to the lower left of Spica.  The next night the moon appears below Saturn.

Venus begins rapid movement into the evening sky after is March superior conjunction.  By month’s end, it is about 9 degrees to the east of the sun and difficult to see. Early next month, it appears in the evening sky near the the waxing crescent moon.  For more about Venus as an Evening Star, see our detailed posting here.

Mars is not visible this month.  On April 18, the Red Planet is behind the sun at conjunction.  It will return to the morning sky during early summer, appearing near Jupiter in the morning of July 22.

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This chart shows the relative positions of Earth, Sun, and Mars on April 18 when Mars is at conjunction.  (Click the image to see it larger.)

Morning Sky

Mercury  lingers in the April predawn sky early in the month, although it rises in mid-twilight.

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On the morning of April 8, the waning crescent moon appears near Mercury.  The chart above shows the pair at 6 a.m. CDT, less then 30 minutes before sunrise.  Find a clear eastern horizon.  Locate the moon with binoculars and then look for Mercury  about 7 degrees to the lower right.  With 7×50 binoculars, the celestial pair may just fit into the binocular field.  Hold the binoculars so that the moon is in the upper left of the field and Mercury may appear to the lower right of the field.  Depending on the binocular, Mercury may appear just outside the view with the moon, so  move the binocular slightly so the moon leaves the field and Mercury enters the view.

By month’s end, the planet is lost in the sun’s glare.

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As viewed from above the chart shows the positions of the visible planets on April 15, 2013.   (Click the image to see it larger.) The sun is between Venus and Mars, making them difficult to observe.  Jupiter is on the evening side of Earth, while Saturn is near opposition as explained above.  Mercury is on the morning side of the sky, but difficult to observe.