Category: Sky Events

Sky events

The Moon and Venus

Tomorrow morning, April 23rd, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 12% crescent a little over 7° from Venus shining at -4.3 magnitude. The pair will rise about an hour before sunrise at about 4am, look for the two just above the brightening glow of dawn.

e Moon, Venus and Aldebaran
The Moon, Venus and Aldebaran join up for an evening conjunction

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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Vernal Equinox

The vernal or spring equinox occurs today at 00:29HST. Today there will be little difference between the length of the night when counted against the number of daylight hours. This is the first day of spring as marked by many cultures in the northern hemisphere.

2017 Solstices and Equinoxes
  UT HST
Perihelion Jan 4 14:18UT Jan 4 04:18HST
Vernal Equinox Mar 20 10:29UT Mar 20 00:29HST
Summer Solstice Jun 21 04:24UT Jun 20 18:24HST
Apehelion Jul 3 20:11UT Jul 3 10:11HST
Autumnal Equinox Sep 22 20:02UT Sep 22 10:02HST
Winter Solstice Dec 21 16:28UT Dec 21 06:28HST
Source: USNO data Services