Magelllan Spacecraft, Arecibo Radio Telescope, NASA file

Magellan spacecraft radar data enabled scientists to penetrate Venus' thick clouds and create simulated views of the surface.

By Joe Rao
Space.com

Enthusiastic skywatchers have perhaps been wondering what has happened lately to Venus, the most brilliant of all the planets.

Since the end of January, Venus has been on a sort of winter and early spring sabbatical. It passed superior conjunction (appearing to go behind the sun as seen from Earth) on March 28 and has been invisible ever since, mired deep in our star's brilliant glare.  

Nevertheless, with each passing day, Venus has been moving on a slow course toward the east and pulling slowly away from the sun’s general vicinity. [Skywatching Events for May 2013]

Finally, during early May, it has begun to emerge as an evening "star" very low in the western twilight. On Saturday evening, it sets 27 degrees north of due west (10 degrees is roughly equal to the width of your fist held at arm’s length) nearly an hour after sunset.

By June 1, Venus will set 80 minutes after sunset, giving even casual observers their first view of the famed "Evening Star." Venus is so bright that it can be spotted even through twilight very low in the west-northwest sky 45 minutes after sunset, so look early, preferably with binoculars.

Appearing as a brilliant white star-like object, Earth's "sister planet" will adorn the western evening sky through the remainder of this year. 

Starry Night Software

A look at the Saturday night sky after sunset. Venus has now moved into the evening sky, and on Saturday it and Jupiter frame the slender crescent moon.

Crummy summer viewing
Unfortunately, for most Northern Hemisphere observers, this is going to turn out to be a rather crummy evening apparition of Venus, especially during the summer months. 

The reason for this lies in Venus’ placement in the sky relative to the sun. From June 19 through Dec. 10, Venus will appear to have a more southerly declination than the sun. As a consequence, it will appear unusually low over the horizon right after sunset, especially through most of this summer. 

On July 1, for example, observers living at or near 40 degrees north latitude will see Venus set just 1 1/2 hours after sunset.  At mid-twilight, the planet will appear to hover only about 6 degrees above the horizon. 

By Aug. 31, this situation will have improved only slightly, as Venus will still be setting only 1 1/2 hours after sundown and at mid-twilight will stand about 8 degrees above the horizon. At no time through July and August will Venus be visible against a completely dark sky, as it will set before the end of evening twilight. [The 10 Weirdest Facts About Venus]

The situation is better in the Southern Hemisphere, where viewers will see Venus pull well away from the sun and gradually soar progressively higher in the evening sky during July and August. For example, by the end of August, Australians will see Venus setting more than three hours after the sun, and the planet will appear more than 20 degrees above the horizon by the end of evening twilight.

An autumn improvement
During September and October, however, the view will begin to slowly improve for northern observers for three reasons:

1) Venus will be getting brighter as it rounds the sun and speeds toward Earth.

2) Twilight fades faster in the fall than in summer, leaving Venus to shine in a darker sky. By mid-September, Venus finally sets just after the sky has become completely dark.

3) Venus will shift over from the west to the southwest. Objects at a given altitude above the horizon in the southern part of the sky take longer to set than do objects at the same altitude in the west, so the difference between the setting times of the sun and Venus will increase, albeit slowly. On Oct. 1, Venus will set 1 3/4 hours after the sun, but this improves to nearly 2 1/2 hours by Halloween.  

Venus reaches its greatest angular distance from the sun on Nov. 1, when it will be 47 degrees east of our star. The planet will be brightest in early December as it heads back down toward the sun, reaching its pinnacle of brilliance for this apparition on Dec. 6 at a lantern-like magnitude of minus 4.9. (On the astronomical scale, lower magnitudes signify brighter objects.)

By this time, Venus will be an eye-catching sight in the southwest sky for at least a couple of hours after sunset right on through the Christmas season. Venus then quickly fades, vanishing from view in early January 2014, and passes inferior conjunction (coming between Earth and the sun) on Jan. 10. Within a week it will re-emerge as the "Morning Star" low in the southeast sky. 

Between now and early January, repeated observation of Venus with a small telescope will show the complete range of its phases and disk sizes. 

The planet is now virtually full (98 percent sunlit), and appears as a tiny, dazzling disk. It will become noticeably less gibbous by late summer. In early November, Venus reaches dichotomy (displaying a half-moon shape). 

Then, for the rest of the year the planet displays a large crescent as it swings near the Earth. Indeed, those using telescopes will note that while the Earth-Venus distance is lessening, the apparent size of Venus’ disk will grow, doubling from its present size by Oct. 9. When it has doubled again in size on Dec. 4, its large crescent shape should be easily discernible even in steadily held 7-power binoculars.

Venus will be one of three bright planets involved in what we at Space.com are billing as "The Grand Conjunction" later this month. Stay tuned for more details!

Editor's note: If you snap an amazing picture of Venus or any other celestial object that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to Managing Editor Tariq Malik at spacephotos@space.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us @Spacedotcom, Facebook or Google+. Originally published on Space.com.

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ESA / VIRTIS-VenusX / INAF-IASF / LESIA-Obs. de Paris (G. Piccioni, INAF-IASF)

This is infrared radiation from the cyclonelike storm circling the south pole of Venus. White regions show cooler, high-altitude clouds.

By Nola Taylor Redd
Space.com

Elements of a giant cyclone circling above the south pole of Venus constantly break apart and re-form, according to new research. Scientists studying observations of the planet taken over the last six years have concluded that the long-lived storm is constantly evolving, raising even more questions about the unusual weather formation.

ESA / VIRTIS / INAF-IASF / Obs. de Paris-LESIA

The large storm at the south pole of Venus rotates once every 2.2 days. Smaller elements of the vortex are constantly being destroyed and re-forming.

A storm on the move
When the European Space Agency's Venus Express satellite arrived at the hot planet in April 2006, it observed a cyclonelike structure above Venus' south pole, four times as large as similar storms on Earth. Over the past six years, the spacecraft has collected daily observations about the storm, which resembles one spotted over Venus' north pole by NASA's Pioneer Venus spacecraft in 1979.

"Both vortices are probably permanent features in the atmosphere of Venus," planetary scientist Itziar Garate-Lopez, of the University of the Basque Country in Spain, told Space.com by email.

Using the observations taken by Venus Express, Garate-Lopez and her team concluded that the giant storm is in constant flux. Elements of the vortex are constantly breaking apart and reforming as it circles every 2.2 days. [Amazing Venus Photos by ESA's Venus Express]

"The vortex is never destroyed, but it evolves continuously between morphologies" or shapes, Garate-Lopez said.

The cause for the constant evolution remains a puzzle that the team still hopes to solve.

ESA / VIRTIS / INAF-IASF / Obs. de Paris-LESIA

A close-up view of the powerful double-eyed storm over the south pole of Venus.

Using the spacecraft's Visible and Infrared Thermal Imaging Spectrometer (VIRTIS), the scientists probed the upper and lower layers of the planet's atmosphere. They concluded that the two centers of rotation of the 12-mile-high (20 kilometers) storm, which exist at different altitudes, rarely line up, a surprising find.

"Even if the small-scale structures are different at both altitude levels, the overall morphology of the vortex is conserved, so we thought that the vortex should move as one large-scale feature in the same way in both vertical layers," Garate-Lopez said. "However, this is not the case."

The constantly shifting centers create what Garate-Lopez calls a "twisted tube" in the vortex.

Although VIRTIS can observe the upper and lower layers of the atmosphere, the middle section remains hidden, keeping the team from more fully understanding the off-kilter movement.

The results were published online Sunday in the journal Nature Geoscience.

A bizarre atmosphere
Venus spins slowly on its axis, taking 243 Earth-days for the sun to rise and set once. But Venus' atmosphere moves significantly faster, circling the planet once every four Earth days.

"The main unsolved question about the atmosphere of Venus is precisely the reason why it super-rotates much faster than the solid planet," Garate-Lopez said.

The relationship between the oddly moving atmosphere and the vortices also remains a mystery.

The cyclone sits 26 miles (42 km) above the surface of the planet. No rain falls from the towering storm, because the planet's atmosphere evaporates all particles within 22 miles (35 km) of the ground. Winds are also inconsequential far beneath the storm.

"If we were at Venus' south pole, we may observe a permanent whirl of clouds high above our heads, with no consequences at the surface," Garate-Lopez said.

Follow Space.com @Spacedotcom, Facebook and Google+. Original article on Space.com.

• Space Weather: Explosions on Venus | Video
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Starry Night Software

At sunrise on Thursday Jan. 10, this will be the naked-eye view of the moon and Venus, low in the southeastern sky.

By Joe Rao, SPACE.com

Early-bird stargazers will have to rise early Thursday, Jan 10 to catch sight of the two brightest objects in the night sky — Venus and the moon — engaged in a final pre-dawn dance. 

To catch the celestial sight, set your alarm clock to ring one hour before sunrise, then quickly head outside. Make sure you go to a viewing site where your east-southeast sky is free of any obstructions such as buildings or trees, since what you’re attempting to see will be poised low above the horizon. 

You’ll be looking for the brilliant planet Venus, and hovering only just above and to its left will be a hairline crescent moon, just 2-percent illuminated and about 32 hours before reaching its new phase. Since the moon became a morning fixture, this will mark the sixth time that it has gotten together with Venus to form an eye-catching configuration.

The moon is very close to us, only 224,000 miles distant, and lit from behind by the sun. Venus, on the other hand, is on the far side of its orbit, on the far side of the sun, 14,724,000 miles away. Because it is on the far side of the sun, it is almost fully illuminated by the sun. In a telescope magnifying 160 times it appears as big as the moon does to our naked eye, and it almost resembles a full moon in its illumination. [ Stargazers' Night Sky Photos for January ]

Unfortunately, this will be the last of such Venus-moon spectacles for some time.

Venus has been a bright morning "star" since it emerged into view shortly after its dramatic transit across the face of the sun late last spring, but now it's finally on its way out. Actually, Venus has slowly been getting lower in the dawn sky for the last four months.

In January, this dazzling orb doesn't even rise until morning twilight is under way, and it is only about 10 degrees up in the sky — the equivalent of your clenched fist held at arm’s length — by the time it fades away in the brightening morning sky. But Venus' great brightness still renders it easily visible in the east-southeast until just before sunrise. 

The sooner you look for Venus this month, the better: By month's end the planet won't  appear over the horizon until after mid-twilight, preceding the sun into the sky by only about 40 minutes.

Although Venus is still three months from superior conjunction with the sun, the fact that it is placed well south of the celestial equator keeps it very low as seen from mid-northern latitudes. As it draws closer to the sun, Venus will drop deeper into the bright morning twilight, eventually being rendered invisible after the first week of February.

Venus will begin to re-emerge very low in the west-northwest evening sky shortly after sunset during the second half of April. From then on, it will spend the rest of 2013 getting progressively higher and more prominent as an evening object. But it won't be until nearly nine months from now, on Sept. 8, that it will again have a close encounter with the moon.

Editor's note: If you snap an amazing photo of Venus and the moon, or any other night sky object, that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at spacephotos@space.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for TheNew YorkTimes and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.Astronomer Geoff Gaherty of Starry Night Education contributed to this report.

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