Venus in the Daytime

With the Moon only a half a degree from Venus this morning, it should be relatively easy to spot the brilliant planet high in the daytime sky.

Crescent Venus
Venus approaching inferior conjunction, 24Dec2013

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 -4.3 magnitude, easily bright enough to see in a clear sky. There are a few helpful hints to make this easier.

Today the Moon will make finding Venus quite easy. The planet is only half a degree above the Moon, just above the slim crescent.  Keep in mind that the Moon is half a degree across, the planet will be half a Moon diameter above the unlit side, easy to spot in the mid-morning sky.  Having the Moon nearby will not only aid in locating the Planet, it will also provide your eyes something to focus on.

The Island Sky for 2019

2019 is looking to be a pretty ordinary year for events, with a few decent events to look forward to. The highlights will be a sunset total lunar eclipse on January 20th, the η-Aquariids meteor shower in early May, a transit of Mercury in November, and a nice set of planetary conjunctions in the sunset and sunrise.

Awaiting dark with the 20" telescope
Andrew Unger beside the 20″ Obsession while waiting for properly dark skies at Kaʻohe

There are dozens of posts scheduled here on DarkerView to remind my readers of these and many more events before they occur. Frankly, I need the reminder myself. Stay tuned for all of the great events the sky of 2019 will offer us.

The remainder of this post is a quick summary of the events our sky has to offer in 2019.

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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 Sky for 2017

Looking ahead to 2017 it appears that the skies will be kind to us this coming year. We have good meteor showers, a total eclipse of the Sun, a bright comet or two, and the usual planetary conjunctions to look forward to. Below you will find some on my notes to what we can look forward to during the coming year.

Jupiter 14Apr2016
Jupiter on April 15, 2016, stack of the best 2000 frames of 7600, Celestron NS11GPS at f/20 and Canon 60D
As is my practice I have spent more than a few evenings loading up DarkerView with scheduled posts for the year. Well over a hundred posts are set as reminders for the interesting astronomical events for 2017. It is a useful effort, as I can see for myself what the year will bring and begin my planning.

Covered are elongations for Mercury and Venus, interesting conjunctions, oppositions, eclipses and meteor showers. Posts include notes for visibility in the Hawaiian islands for those events that are location dependent.

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Solar System Walk 2016

Walking from the Sun to Neptune is easy… At least when they are set up in a scale model along main street Waimea.

A fun day… The Sun, telescopes, the planets, a few asteroids represented by meteorites, and plenty of activities for the kids. It was a great day to be in Waimea as CFHT and Keck put on the Solar System Walk 2016…

Long-term, hi-res tracking of eruptions on Jupiter’s moon Io

UC Berkeley press release

NIRC2 image of Io
A NIRC2 image of Jupiter’s Moon Io
Jupiter’s moon Io continues to be the most volcanically active body in the solar system, as documented by the longest series of frequent, high-resolution observations of the moon’s thermal emission ever obtained.

Using near-infrared adaptive optics on two of the world’s largest telescopes — the 10-meter Keck II and the 8-meter Gemini North, both located near the summit of the dormant volcano Maunakea in Hawaii — UC Berkeley astronomers tracked 48 volcanic hot spots on the surface over a period of 29 months from August 2013 through the end of 2015.

“On a given night, we may see half a dozen or more different hot spots,” said Katherine de Kleer, a UC Berkeley graduate student who led the observations. “Of Io’s hundreds of active volcanoes, we have been able to track the 50 that were the most powerful over the past few years.”

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The Moon and Jupiter

This evening at sunset a nice crescent Moon and the bright planet Jupiter will be quite close. As sunset around 19:00 the two will be separated by a mere 46′, just a little over the width of the full Moon. The two should make a very attractive pair as they sit above the glow of sunset.

Keep an eye out for Mercury and Venus closer to the horizon. At 19:00 Venus will be 9° above the horizon with Mercury a bit higher at 14°. The Moon and Jupiter will be higher yet around 25°. Since Mars and Saturn are also visible in the southern sky all five naked eye planets will be visible.

All Five Planets Visible

For much of the month all five naked eye planets will be visible at sunset. Mercury, Venus, Mars, Saturn, and Jupiter can all be seen easily if one knows where to look. Indeed, four of the five are quite bright and quite hard to miss. Neptune and Uranus are generally too faint to be seen without optical aid.

Venus and Jupiter over the Keck 1 dome
Tonight, August 1st, Venus is just rising high enough to be easily seen. It will be a mere 5° above the horizon at 19:30, probably bright enough to be seen against the glow. You can find Mercury a little higher, about 10° above the horizon. Jupiter is obvious well above the sunset as a bright object shining at -1.7 magnitude. Mars and Saturn are visible to the south on the top of Scorpio.

There will be a nice conjunction of the Moon and Jupiter, only 46′ apart, on the 5th of August. Mercury reaches eastern elongation on the 16th of the month. A beautiful triplet of Mercury, Venus, and Jupiter will gather in the days around the 22nd. Keep an eye to the sky for the month to be treated to some nice planetary views.

Caltech Researchers Find Evidence of a Real Ninth Planet

Caltech press release

Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.

Planet 9 Artist's Concept
This artistic rendering shows the distant view from Planet Nine back towards the sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Hypothetical lightning lights up the night side. Credit: Caltech/R. Hurt (IPAC)
The researchers, Konstantin Batygin and Mike Brown, discovered the planet’s existence through mathematical modeling and computer simulations but have not yet observed the object directly.

“This would be a real ninth planet,” says Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy. “There have only been two true planets discovered since ancient times, and this would be a third. It’s a pretty substantial chunk of our solar system that’s still out there to be found, which is pretty exciting.”

Brown notes that the putative ninth planet—at 5,000 times the mass of Pluto—is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighborhood of the solar system. In fact, it dominates a region larger than any of the other known planets—a fact that Brown says makes it “the most planet-y of the planets in the whole solar system.”

Batygin and Brown describe their work in the current issue of the Astronomical Journal and show how Planet Nine helps explain a number of mysterious features of the field of icy objects and debris beyond Neptune known as the Kuiper Belt.

“Although we were initially quite skeptical that this planet could exist, as we continued to investigate its orbit and what it would mean for the outer solar system, we become increasingly convinced that it is out there,” says Batygin, an assistant professor of planetary science. “For the first time in over 150 years, there is solid evidence that the solar system’s planetary census is incomplete.”

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Mercury Appears in the Evening Sky

The planet Mercury is starting an evening apparition. The planet should become visible this week just above the fading glow of the setting Sun as a magnitude -1 object. The planet is moving about 1° further from the Sun and higher in the sunset each day, reaching a maximum elongation of 20° on December 28th.

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