The Moon and Venus

Tomorrow morning, June 20th, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 18% crescent a little under 6° from Venus shining at -4.2 magnitude. The pair will rise about three hours before sunrise at about 2am, look for the two above the brightening glow of dawn.

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

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.

Continue reading “Venus at Maximum Elongation”

The Moon and Venus

Tomorrow morning, May 22nd, a pretty crescent Moon will be located close to a brilliant Venus. The Moon will be a slim 15% crescent a little over 3° from Venus shining at -4.4 magnitude. The pair will rise about two hours before sunrise at about 3am, look for the two above the brightening glow of dawn.

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

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

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

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.

Continue reading “Venus at Inferior Conjunction”

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

Venus Becomes a Crescent

Even when Venus is high in the sky and well placed for observation I will seldom take the effort of turning a telescope towards the planet. Why? Because Venus is pretty boring to look at. Perpetually cloud covered it has all the detail of a cue ball. It is a white disk with nothing of note to be seen. Yeah, pretty boring. Now turn the telescope to Jupiter.

Crescent Venus
Venus approaching inferior conjunction, 24Dec2013
One exception to this occurs when Venus is approaching, or just emerging from inferior conjunction. As the planet passes between the Earth and the Sun we are looking at the nighttime side of the planet, with only a little of the daytime side to be seen. As a result Venus will appear as a brilliant crescent.

This begins as the planet passes maximum eastern elongation, about two months before inferior conjunction. At this point the planet is seen from the side with respect to the sunlight, the planet will be about half illuminated. In the weeks after maximum elongation the planet will appear ever more crescent.

Venus 28May2012
Venus on 28May2012, about 12°44′ from the Sun
The last weeks before conjunction, as Venus is very low in the sunset, or the first weeks after conjunction as it sits very low in the dawn are the most interesting. During this time the planet is a very fine crescent, quite a beautiful sight in the telescope. Many observers, including myself, have made a point to observe Venus at this time, the one time this planet really becomes interesting to view.

Imaging Venus in the Daytime
Imaging Venus in the daytime a mere 12°44′ from the Sun.
As the planet is quite low in the sky it makes it a challenging telescopic target and distortion by the atmosphere can be troubling, blurring the view.

It is possible to enjoy this sight in the daytime, while the planet is high in the sky, the seeing can be better and the view sharper. Of course this also occurs when the planet is near the Sun, thus extreme caution should be practiced at the telescope to avoid any direct sunlight and possible eye damage.

Planetary Drawings by Galileo
A page from Galileo’s 1623 treatise The Assayer—Il Saggiatore
The phases of Venus are quite interesting from a historical standpoint. The phases of Venus clearly show that the planet revolves around the Sun. The phases were one of the primary arguments used by Galileo in his treatise The Assayer—Il Saggiatore published in 1623, where he lays out many of his ideas on science itself and how observation and experimentation should be primary.

While the the evidence challenged prevailing ideas of the time, some astronomers attempted to explain the phases of Venus by any other means to preserve their Earth centered universe, which led to rather tortured models of planetary motion. But it was clear to most that Galileo was right, the simple and elegant answer was that the Sun lay at the center. The orbits of Mercury and Venus, the phases, along with other observations like the moons of Jupiter, were hard evidence that few could ignore.

In 2017, eastern elongation occurred on January 12th. By now Venus has begun to show a substantial crescent, about 30% illuminated if you look today, Feb 12th. Over the next few weeks as the planet sinks into the sunset, the crescent aspect will thin dramatically.

By the end of February the planet will be only 17% illuminated, another week after that it becomes only 11%, by which time the planet will be difficult to spot in the sunset. Inferior conjunction will occur on March 25th. A couple weeks later and it will be possible to spot the planet in the dawn and observe the now thickening crescent.

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

The Moon, Venus and Mars

The Moon, Venus and Jupiter
A morning conjunction of the three brightest objects in the night sky, the Moon, Venus and Jupiter on the morning of July 15, 2012, the Pleiades star cluster can be seen at the top
This evening a pretty crescent Moon will slide past Venus and Mars in the sunset. The Moon will be a slim 16% crescent a little over 5° from Venus shining at -4.6 magnitude.

Look for the trio in the western sky this evening just after sunset, it will be nearly impossible to overlook. You have plenty of time to enjoy the show as the trio will not set until around 9:30pm.

Venus in the Daytime

With the Moon only a few degrees from Venus this afternoon, it should be relatively easy to spot the brilliant planet long before sunset.

Venus 28May2012
Venus photographed on 28May2012, about 13° from the Sun in the mid-afternoon sky
Spotting planets in the daytime is not that difficult, both Jupiter and Venus are bright enough to seen in full daylight. Venus is currently near maximum brilliance at about -4.6 magnitude, easily bright enough to see in a clear sky. There are a few helpful hints to make this easier.

Today the Moon will aid finding Venus in the sky as it is about 5° north of the Moon. Having the Moon nearby will not only aid in locating the Planet, it will also provide your eyes something to focus on.

Of course these bright objects will be even more dramatic after sunset when Mars will also be visible nearby.