Mercury at Superior Conjunction

Today Mercury will be at superior conjunction. After today the planet will reappear in the evening sky, rising high enough from the Sun’s glow to be seen early next month.

Mercury Transit 9May2016
Mercury transiting the Sun on May 9, 2016. Celestron C8 and Canon 6D at f/10.
Superior conjunction is when the planet passes around the far side of the Sun as seen from Earth. For a few weeks the planet will be lost in the Sun’s glare, hidden from view.

As Mercury is on an orbit inside that of Earth’s it will see both inferior and superior conjunctions as it passes from the evening sky to the dawn sky and back again.

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Saturn at Opposition

Today the planet Saturn will pass through opposition, directly opposite the Sun in our sky.

Saturn 22Apr2010
Saturn with Titan above
Saturn orbits the Sun once every 29.45 years. As the ringed planet continues on its way the Earth swings around much faster on our inside track. As a result we lap Saturn once every 378.1 days, passing between the planet and the Sun. During opposition Saturn will be well placed for observation all night long, rising at sunset, transiting at midnight, and setting at sunrise.

During opposition the planet and rings will be slightly brighter than normal, an effect known as the opposition effect. The effect is most notable in the rings where the apparent brightness can increase by 30%. The effect is a combination of two factors, shadow hiding and the retro-reflective properties of the ring particles.

Venus at Maximum Elongation

Today Venus is at maximum elongation, as high in the dawn sky as it will get for this morning apparition, about 45.9°. After today the planet will begin its slide back into the glare of dawn. It will disappear from view around the end of the year and reach superior conjunction on January 8th, 2018.

As Earth and Venus race about the Sun, Venus will complete about one cycle of appearances each year. We can expect one evening apparition and one morning apparition to occur in 2017.

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Mercury at Maximum Elongation

Today Mercury will be at maximum western elongation, as high in the morning sky as it will appear for this current apparition. After today the planet will slide back into the dawn, passing through superior conjunction on June 21st to reappear in the evening in mid-July.

Mercury Transit 9May2016
Mercury transiting the Sun on May 9, 2016. Celestron C8 and Canon 6D at f/10.
This will be the best morning apparition of the inner planet for 2016. The best evening apparition of 2017 will be in July, with a maximum elongation of over 27°.

There are no transits of Mercury in 2017, the next will be Nov 11, 2019.

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Mercury at Inferior Conjunction

Today Mercury will be at inferior conjunction. After today the planet will reappear in the dawn, rising high enough from the Sun’s glow to be seen around the end of the month.

Mercury Transit 9May2016
Mercury transiting the Sun on May 9, 2016. Celestron C8 and Canon 6D at f/10.
Inferior conjunction is when the planet passes between the Sun and the Earth. As such the only planets to see inferior conjunction are Mercury and Venus. A transit is possible if the planet passes directly in front of the Sun, but normally this alignment does not occur, the planet passing above or below the Sun as seen from the Earth. There are no transits of Mercury in 2017, the next will be Nov 11, 2019.

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Jupiter at Opposition

Jupiter will pass through opposition at 10:58HST today.

Jove
Jupiter and the moons Europa, Ganymede and Callisto (left-right)
Jupiter orbits the Sun once every 11.86 years. As the giant planet continues on its way the Earth swings around much faster on our inside track. As a result we lap Jupiter once every 399 days, passing between the planet and the Sun. During opposition Jupiter will rise at sunset, transit at midnight, and set at dawn. This makes the planet available for observation for the entire night.

Look for a bright object rising in the eastern sky after sunset. It is difficult to mistake for anything else, shining at it’s brightest during opposition, a brilliant -2.7 magnitude. For the remainder of the spring and much of the summer, the planet will be quite prominent in the evening sky.

Venus Appears in the Dawn

The bright planet Venus will appear in the dawn sky over the next couple weeks, climbing higher to become the morning star for the remainder of 2017. It is currently 15° from the Sun and shining at magnitude -4.3, bright enough to be seen against the dawn sky. It will reach maximum elongation on June 3rd, 46° ahead of the rising Sun.

Venus Events for 2017

  Date UT Separation Mag
Maximum Elongation Jan 12 47.1°E -4.4
Inferior Conjunction Mar 25    
Maximum Elongation Jun 3 45.9°W -4.3
 
Source: NASA Sky Calendar

Mercury at Maximum Elongation

Today Mercury will be at maximum eastern elongation, as high in the evening sky as it will appear for this current apparition. After today the planet will slide back into the sunset, passing through inferior conjunction on April 19th to reappear in the morning sky around the end of the month.

Mercury Transit 9May2016
Mercury transiting the Sun on May 9, 2016. Celestron C8 and Canon 6D at f/10.
Mercury typically completes three morning and three evening apparitions in each year. While the innermost planet never gets very far from the Sun, maximum elongation represents the best time to observe Mercury as high in the sky as possible.

There are no transits of Mercury in 2017, the next will be Nov 11, 2019.

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Venus at Inferior Conjunction

Today Venus is at inferior conjunction, passing between the Earth and Sun. It will reappear in the dawn sky early next month to become the morning star for the remainder of 2017. The planet will reach maximum elongation on June 3rd at 46° from the Sun.

Crescent Venus
Venus approaching inferior conjunction, 24Dec2013
As Venus emerges from the Sun’s glare it will be a fine crescent, growing thicker each day as we see more of the sunlit side of the planet. While it is still low in the dawn it can be a fine telescopic target. It is these phases of Venus that Galileo noted 400 years ago, one more bit of evidence to the true, Sun centered, nature of our solar system.

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Venus Exits the Evening Sky

Over the next week Venus will be lost to the Sun’s glare. It is currently about 15° east of the Sun, but getting closer quite quickly now and becoming tough to spot in the sunset. The planet will pass through inferior conjunction on March 25th. The planet will appear in the dawn sky around mid April. When it does appear, it will spend the remainder of 2017 as the morning star.

Crescent Venus
Venus approaching inferior conjunction, 24Dec2013
Even when low in the sunset, Venus is worth picking up in a telescope. As the planet approaches inferior conjunction it shows an ever more crescent appearance to our earthbound vantage point. During the last days of visibility it will be a razor thin crescent, worth the effort to look.

Venus Events for 2017

  Date UT Separation Mag
Maximum Elongation Jan 12 47.1°E -4.4
Inferior Conjunction Mar 25    
Maximum Elongation Jun 3 45.9°W -4.3
 
Source: NASA Sky Calendar