2017: Mercury’s Spring Evening Appearance

Mercury’s best evening appearance at mid-northern latitudes occurs during spring evenings.  This year, Mercury appears farthest from the sun on April 1.  A few days earlier (March 29), the moon helps in locating this speedy and elusive planet.  Look to the west at 8 p.m. CDT as observed from the Chicago area.  For other time zones, look about 45 minutes after sunset.  The crescent moon stands nearly 13 degrees above the western horizon.  Mercury is about 9 degrees to the lower right of the moon.  In typical 7 x 50 binoculars, Mercury stands just outside the field of view if the moon is placed at the 10 o’clock part of the field.  Slowly move the binocular toward the 4 o’clock direction.  Mercury will appear in view.

Mars is fading in brightness quickly and appears 11 degrees above the moon.

Link to YouTube video.

For more information about Mercury’s evening appearances this year, see this article:

For more information about current sky events, see these articles:

2017: Locating Planets During Twilight

Showing a friend the location of the planet in a clear blue sky is a challenge.  If the moon is nearby, as in the image above, then locating the planet is easier.

If the sky is clear without clouds or the moon, then it’s more challenging.  In the image above we found Venus in the sky.  Some persons in the party could not find the planet.  We moved to a place where Venus was just above a nearby tree.  We said, “Look for Venus immediately above the tree.”  It was much easier to see in the sky than it appears in the image above.  Happy planet searching.

For more information about current sky events, see these articles:

2017, Late March: Venus as a Morning and an Evening Star

This is likely visible only with optical assistance, such as through binoculars or a small telescope.  WARNING!  NEVER POINT BINOCULARS OR TELESCOPE DIRECTLY AT THE SUN!   Such activity can cause permanent damage to your vision and/or the optical device.

As Venus rapidly disappears into the sun’s brightness during the next few weeks of March, it is visible in the morning sky and evening sky with optical assistance.  (Not to be redundant, but heed the warning above.)

Venus reaches inferior conjunction on March 25, 2017.  At this time Venus moves between the Earth and the sun.  Because the orbits  of the planets line nearly in a plane, but not a perfect one, Venus does not move directly across the face of the sun.  It either passes above or below the sun.

At this conjunction, Venus is about 8 degrees above or north of the sun.  When an object is north of the sun, it can appear in both the morning and evening sky.  The Big Dipper is far north of the sun.  In March, during the early evening from mid-northern latitudes, the Big Dipper appears to stand on its handle high in the northeast.  In the predawn hours, it appears to be dipping down from the northwestern sky.  The Big Dipper is an extreme case of the concept.  But is shows that anything north of the sun can be both seen in the morning sky and in the evening sky,

The chart above (click the image to see it larger), shows Venus’ invisible orbit at noon on inferior conjunction day.  With appropriate shading, the planet is visible with optical assistance.  It is north of the sun.

Starting at mid-March and until inferior conjunction, Venus rises just ahead of the sun in the morning and sets just after it in the evening, during bright twilight, and so the need for optical assistance.  The optimum date is March 22 when Venus rises about 30 minutes before the sun and sets 30 minutes after.

At 6:45 a.m. CDT in the Chicago are (check your local sunrise time for other locations), about 10 minutes before sunrise, Venus stands 4 degrees above the the horizon and about 11 degrees from the sunrise point.  A crescent moon is in the southeast, over 70 degrees from Venus and not much help with its identification.

That evening, about 15 minutes after sunset (7:10 p.m. CDT in the Chicago area), Venus is 4 degrees above the horizon and 8 degrees from the sunset point.  Dimmer Mercury is about 13 degrees to the upper left of Venus.

While not easily seen, it is possible to see Venus as both a morning and evening star.

For more information about current sky events, see these articles:

2017, February 10: Lunar Eclipse Photo

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Penumbral Lunar Eclipse, February 10, 2017. Photo by Tim S.

This photo of the February 10, 2017 penumbral lunar eclipse shows darkening on the upper edge of the moon.  Skies clear in the region after the maximum part of the eclipse.

For more information about current sky events, see these articles:

2017: Venus as a Morning Star

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Venus last appeared in the morning sky in 2015 and 2016, when it appeared with Mars and Jupiter.

Introduction

Brilliant Venus zips into the morning sky during April  2017 and dominates the morning sky until year’s end.   During this morning appearance, Venus makes close appearances with the star Regulus and the planets Jupiter and Mars.

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This chart shows the rising time of bright planets, the moon, and stars near the planets’ orbital plane (ecliptic) compared to sunrise as calculated from U.S. Naval Observatory data for Chicago, Illinois in the Central Time Zone.  Additionally, the times when Jupiter sets and Saturn sets are charted compared to sunrise.  On April 7, Jupiter is at opposition and it sets in the west at sunrise.  The time differences are also displayed for Civil Twilight, Nautical Twilight and Astronomical Twilight.  At Astronomical Twilight, the sky is as dark as it gets naturally.

The rising time of Venus is represented by the green line on the chart.  It enters the chart in mid-March, reaching its maximum rising time difference during the summer, and leaves the sky in early 2018.  Notice that during the summer months of this appearance of Venus, the brilliant planet rises well before the beginning of twilight.  It stands low in the eastern sky as the sky brightens.

As Venus appears earlier in the morning sky, Jupiter shines brightly in the western sky, until about May 20 when Jupiter sets as Venus rises. (Notice on the chart, Jupiter sets line crosses the Venus rises at May 20.)  After this date Jupiter sets before Venus rises.  Similarly, Saturn, while not as bright as Jupiter or Venus, reaches opposition on June 15, setting in the west as Venus rises in the eastern sky.  Venus appears in the eastern morning sky and Saturn appears in the western sky until about July 25 when Saturn sets as Venus rises.  After this date Saturn sets before Venus rises.

Later in the year, Venus appears near Regulus.  This occurs near the date when the rising lines of Regulus and Venus intersect.  The same occurs for Mars, Spica, and Jupiter.  As Venus moves back into bright sunlight later in the year, it appears near Mercury, Antares and Saturn, although they appear together during bright twilight and out of view for most observers.

Venus has a close conjunction with Mars on October 5, followed by a very close (Epoch) conjunction with Jupiter on November 13.

The moon passes Venus each month, as our nearest celestial neighbor moves through its celestial path.  Two dates (May 22 and July 20) are especially noteworthy when Venus and the moon appear about 3.5 degrees apart.

Inferior Conjunction

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Venus moves between Earth and Sun on March 25, 2017; this is known as inferior conjunction.  Since Venus has a shorter orbital path and faster speed, it quickly moves into the morning sky.  The red line on the chart shows the division between morning and evening.  The line pointing from the earth to the sun indicates noon.  So at inferior conjunction, Venus rises with the sun, appears in the south at noon, and sets in the west at sunset.

Venus does not appear in the sky at midnight at mid-northern latitudes.  That occurs when a planet is opposite the sun in the sky as seen from Earth.  On the chart notice that the midnight line does not point toward Venus.

As Venus reaches this inferior conjunction, it passes above the sun.  Because it is north, above the sun, it rises earlier than the sun.  On conjunction morning it rises about 40 minutes before the sun.  On the rising chart above, it first appears on the chart on March 14, 11 days before it reaches conjunction!

Venus was last at inferior conjunction on August 25, 2015, 589 days between inferior conjunctions.

Greatest Brightness

The planet rapidly moves into the morning sky, rising earlier each morning.  It is very close to our planet and sparkles in the morning sky.  The brightness is from the proximity of the planet to Earth, its highly reflective clouds and the phase of the planet.  (Yes, Venus shows phases when viewed through a telescope.)  At this time Venus is about 170 times the moon’s distance, relatively close compared to other planets.

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From April 15 through May 13, Venus appears brightest in our skies, with the mid-point on May 1, 2017.  This is shown with the GB (greatest brightness) designation on the rising chart above.

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Venus continues to rise earlier each morning. On the morning of May 22, the crescent moon appears about 3.5 degrees from Venus.

Greatest Elongation

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Venus reaches its greatest angular separation (46 degrees) from the sun on June 3.  This is shown by the GE symbol (greatest elongation) on the rising chart above.  It rises about 2 hours before sun near the beginning of twilight.

Venus Dazzles Morning Sky

 Venus continues rising earlier as summer begins.

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On July 14, Venus moves past Aldebaran.  The closest approach is about 4 degrees.

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The Binocular View

More striking is the star cluster near Venus and Aldebaran: Hyades.  The Hyades cluster is about 2.5 times farther away than ruddy Aldebaran.  Through binoculars, Venus, Aldebaran and the jewel-like stars of the cluster sparkle against the black velvet of the  predawn sky. Several dozen stars can be seen.

To the unaided eye, the Hyades resemble a check mark or a letter “V” if Aldebaran is included.

Clusters, like the Hyades, are used to refine distance measuring techniques as well descriptions of the lives of stars.  These clusters are thought to form at approximately the same time.  Stars that burn their nuclear fuels faster convert into other stellar forms sooner, such as red giants and red super giants.  From these stellar models, the estimate of the sun’s total lifespan is about 10 billion years.

Over time these clusters break apart; the gravitational forces between the stars are not strong enough to keep the cluster together.  The stars go their own way in their orbital path around the galaxy.

Our sun was likely formed in such a cluster and is now a lone star since it has gone into its own orbit around the Milky Way galaxy.

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On the morning of July 20, the crescent moon again appears with Venus.  The pair is separated by about 3.5 degrees.

In early August Venus rises about 3 hours before sunrise and begins to rise later each morning as displayed on the rising chart.  For the rest of the year, it loses about 30 minutes each month.

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In late summer and early Autumn look for Venus and Sirius at the same time.  Both are about the same height (altitude) above the eastern horizon.  Venus stands in the east-northeast and Sirius appears in the southeast.  Only the sun and moon shine brighter than Venus and Sirius is the brightest star in the night sky. See this link to view the last time Venus and Sirius appeared together in the morning sky.

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Venus continues its rapid eastward movement as compared to the stars and descent toward the sun’s glow, passing about a half degree from Regulus on September 20.  This pair rises about 2 hours before sunrise.

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Over a month later, Venus passes Spica.  The gap is nearly 4 degrees.

Mars Conjunction

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The first planetary conjunction of this appearance is with Mars.  On the morning of October 5, Venus passes 0.2 degrees from the Red Planet.  The planets are close on a few mornings before and after the conjunction.

Venus-Jupiter Epoch Conjunction

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Another Epoch (close) Conjunction of Venus and Jupiter occurs before sunrise on November 13.  The distance is about .2 degrees.  This conjunction is visible during twilight as the pair rises about 70 minutes before the sun.

The next conjunction between the pair is November 24, 2019 with the next epoch conjunction on April 30, 2022.

Superior Conjunction

Venus continues its rapid descent into bright sunlight.  Conjunctions occur with Mercury, Antares and Saturn, but they occur in bright twilight, out of the view of most observers.

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On January 9, 2018 passes behind the sun at its superior conjunction and reappears in the evening sky.

Lunar Conjunctions

The moon appears with Venus on the following dates:

April 23: 8 degrees
May 22: 3.5 degrees (See description in text)
June 20: 7 degrees
July 20: 3.5 degrees (See description in text)
August 19: 4.5 degrees
September 17: 6 degrees
October 18: 5.5 degrees

Venus provides a dazzling view of planetary, stellar and conjunctions during its morning appearance in 2017.

2017, February 1: Venus, Mars & the Moon

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Brilliant Venus shines through thin clouds this evening.  Dimmer Mars is 5.5 degrees to the upper left of Venus and the Moon is 11.5 degrees above Mars.  The planets are closest on February 3.  Venus does not pass Mars at this appearance.

For more information about the Venus-Mars encounters and other planet observations, see these articles:

2017, February: Sky Watching

Orion Nebula (NASA Photo)

Orion Nebula (NASA Photo)

The constellation Orion is visible high in the southern skies during the early evening hours of February.  It is easily recognizable by its three stars of nearly equal brightness that mark his belt.  Within his sword is a gently glowing nebula.  Through binoculars or a small telescope it appears as a greenish cloud with stars in it.  The Hubble Space Telescope gathered the light of this distant stellar nursery to make this colorful, dynamic image shown above.

Sun

The length of daylight increases by 70 minutes this month.  The sun rises and sets farther north and appears 9 degrees higher at noon by month’s end.  The rising and setting directions move about 12 degrees northward during the month.  In the Chicago area, the sun rises before 7 a.m. the first time this year on February 5.

There is an annular solar eclipse on February 26, although it is only visible from the southern hemisphere (Pacific Ocean, South America, Atlantic Ocean, and Africa.)

Moon

NASA Photo

NASA Photo

Phase Date/Time Moon rise Moon set
First Quarter 02/03/17 (10:19 p.m.) 10:51 a.m. 11:31 p.m.
Full Moon 02/10/17 (6:33 p.m.) 5:13 p.m. 7:10 a.m. (02/11/17)
Last Quarter 02/18/17 (1:33 p.m.) 12:19 a.m. 10:52 a.m.
New Moon 02/26/17 (8:58 a.m.) 6:34 a.m. 5:55 p.m.
Times are Central Standard Time for Chicago, Illinois, from US Naval Observatory calculations.
(For mjb & afb)

There is a penumbral lunar eclipse on the evening of February 10, although the moon will not display is classic reddish eclipse color.  During this eclipse the moon passes through the earth’s outer shadow that is quite bright.  Casual observers will not see much change in the moon’s brightness during the eclipse.  The eclipse is visible across most of the planet except for eastern Asia and Australia.  In the Chicago area, the moon rises in the in the east-northeastern sky at 5;13 p.m. CST with the eclipse in progress.  As the moon rises higher, the eclipse progresses.  The maximum eclipse is at 6:33 p.m. CST when the moon is officially full.  (See the time of the full moon above.) The eclipse ends at 8:53 p.m. CST.

Evening Sky

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Gleaming Venus shines brilliantly from the western sky as the month opens.  Dimmer Mars is about 5.5 degrees to the upper left of Venus and the crescent moon is another 11 degrees above Mars.

The planets are closest on February 3, still over 5 degrees apart.  Venus does not pass Mars; after this closest appearance, Venus rapidly moves toward the sun’s brilliance.

Beginning February 4 and lasting for nearly a month, Venus reaches its greatest brightness, with the mid-point date on February 18.  This period of greatest brilliancy occurs when Venus and Earth are near each other.  During this time, the distance to Venus is about 39 million miles, about 160 times the moon’s distance.  Venus is nearing its inferior conjunction when it passes between Earth and the sun, so it appears larger when viewed through a telescope than when it is near its superior conjunction on the far side of the sun.  This combined with its highly reflective clouds makes it appear to be the brightest star in the sky.

For More about Venus in the evening sky and its close approach to Mars, see these articles:

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By month’s end, the moon appears again in the western sky after sunset.  On February 28, it appears about 10 degrees to the lower right of Venus with Mars 12 degrees to the upper left of Venus.

Morning Sky

Meanwhile, Jupiter shines brightly from the southern skies with the star Spica.  The pair rises in the southeast at around 11 p.m. and are well placed in the southern sky before sunrise.  Jupiter’s proximity to Spica is part of a triple conjunction — that is, Jupiter passes Spica three times during a single apparition.  Jupiter first passed Spica on January 20, by about 3.5 degrees.

During early February, Jupiter appears to begin to backup, retrograde, and passes Spica again on February 23.  The third conjunction occurs on September 9.

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The waning gibbous moon joins Jupiter and Spica on the morning of February 15.  The moon is 3.5 degrees from Jupiter and Spica is nearly the same distance below Jupiter.  For more about Jupiter’s triple conjunction with Spica, see this article:

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Saturn is easier to locate in February.  It rises at about 4 a.m. at the beginning of the month.  It rises earlier each day.  By February 20, the moon appears about 6 degrees to the upper right of Saturn.  On the next morning the moon appears about 6 degrees below Saturn.

February offers four bright planets and a host of bright stars for easy viewing.  Dress warmly, step outside and take a look.