Earth’s Twisted Sister: How Will We Reveal Venus’ Secrets?

A radar view of Venus taken by the Magellan spacecraft, with some gaps filled in by the Pioneer Venus orbiter. Credit: NASA/JPL

Venus is known as Earth’s Sister Planet. It’s roughly the same size and mass as Earth, it’s our closest planetary neighbor, and Venus and Earth grew up together.

When you grow up with something, and it’s always been there, you kind of take it for granted. As a species, we occasionally glance over at Venus and go “Huh. Look at Venus.” Mars, exotic exoplanets in distant solar systems, and the strange gas giants and their moons in our own Solar System attract much more of our attention.

If a distant civilization searched our Solar System for potentially habitable planets, using the same criteria we do, then Venus would be front page news for them. It’s on the edge of the habitable zone and it has an atmosphere. But we know better. Venus is a hellish world, hot enough to melt lead, with crushing atmospheric pressure and acid rain falling from the sky. Even so, Venus still holds secrets we need to reveal.

Chief among those secrets is, “Why did Venus develop so differently?

Conditions on Venus pose unique challenges. The history of Venus exploration is littered with melted Soviet Venera Landers. Orbital probes like Pioneer 12 and Magellan have had more success recently, but Venus’ dense atmosphere still limits their effectiveness. Advances in materials, and especially in electronic circuitry that can withstand Venus’ heat, have buoyed our hopes of exploring the surface of Venus in greater detail.

At the Planetary Science Vision 2050 Workshop 2017, put on by the Lunar and Planetary Institute (LPI) a team from the Southwest Research Institute (SWRI) examined the future of Venus exploration. The team was led by James Cutts from JPL.

The group acknowledged several over-arching questions we have about Venus:

How can we understand the atmospheric formation, evolution, and climate history?
How can we determine the evolution of the surface and interior?
How can we understand the nature of interior-surface-atmosphere interactions over time, including whether liquid water was ever present?

Since the Vision 2050 Workshop is all about the next 50 years, Cutts and his team looked at the challenges posed by Venus’ unique conditions, and how they could answer questions in the near-term, mid-term, and long-term.

Near Term Exploration (Present to 2019)

Near-Term goals for the exploration of Venus include improved remote-sensing from orbital probes. This will tell us more about the gravity and topography of Venus. Improved radar imaging and infrared imaging will fill in more blanks. The team also promoted the idea of a sustained aerial platform, a deep probe, and a short duration lander. Multiple probes/dropsondes are also part of the plan.

Dropsondes are small devices that are released into the atmosphere to measure winds, temperature, and humidity. They’re used on Earth to understand the weather, and extreme phenomena like hurricanes, and can fulfill the same purpose at Venus.

Dropsondes are released into the atmosphere, and their descent is slowed by a small parachute. As they descend, they gather data on temperature, wind, and humidity. Image By Staff Sgt. Randy Redman of the US Air Force

In the near-term, missions whose final destination is not Venus can also answer questions. Fly-bys by craft such as Bepi-Colombo, Solar Probe Plus, and the Solar Orbiter missions can give us good information on their way to Mercury and the Sun respectively. These missions will launch in 2018.

Bepi-Colombo, a joint mission of the ESA and JAXA, will perform two fly-bys of Venus on its way to Mercury. Image: ESA/JAXA

The ESO’s Venus Express and Japan’s Akatsuki, (Venus Climate Orbiter), have studied Venus’ climate in detail, especially its chemistry and the interactions between the atmosphere and the surface. Venus Express ended in 2015, while Akatsuki is still there.

Mid-Term Exploration (2020-2024)

The mid-term goals are more ambitious. They include a long-term lander to study Venus’ geophysical properties, a short-duration tessera lander, and two balloons.

The tesserae lander would land in a type of terrain found on Venus known as tesserae. We think that at one time, Venus had liquid water on it. The fundamental evidence for this may lie in the tesserae regions, but the terrain is extremely rough. A short duration lander that could land and operate in the tesserae regions would help us answer Venus’ liquid water question.

Thanks to the continued development of heat-hardy electronics, a long-term duration lander (months or more) is becoming more feasible in the mid-term. Ideally, any long-term mobile lander would be able to travel tens to hundreds of kilometers, in order to acquire a regional sample of Venus’ surface. This is the only way to take geochemistry and mineralogy measurements at multiple sites.

On Mars the landers are solar-powered. Venus’ thick atmosphere makes that impossible. But the same dense atmosphere that prohibits solar power might offer another solution: a sail-powered rover. Old-fashioned sail power might hold the key to moving around on the surface of Venus. Because the atmosphere is so dense, only a small sail would be necessary.

A simple sail-powered rover may solve the problem of mobility on the Venusian surface. Image: NASA

Long-Term Exploration (2025 and Beyond)

The long-term goals from Cutts and his team are where things get really interesting. A long-lived surface rover is still on the list, or possibly a near-surface craft like a balloon. Also on there is a long-lived seismic network.

A seismic network would really start to reveal the secrets behind Venus’ geophysical life. Whereas a lander would give us estimates of seismic activity, they would be crude compared to what a network of seismic sensors would reveal about Venus’ inner workings. A more thorough understanding of quake mechanisms and locations would really get the theorists buzzing. But it’s the final thing on the list that would be the end-goal. A sample-return mission.

We’re getting good at in situ measurements on other worlds. But for Venus, and for all the other worlds we have visited or want to visit, a sample return is the holy grail. The Apollo missions brought back hundreds of kilograms of lunar samples. Other sample-return missions have been sent to Phobos, which failed, and to asteroids, with varying degrees of success.

Subjecting a sample to the kind of deep analysis that can only be done on labs here on Earth is the end-game. We can keep analyzing samples as we develop new technologies to examine them with. Science is iterative, after all.

An artist’s image of Hayabusa leaving Earth. Hayabusa was a Japanese sample return mission to the asteroid 25143 Itokawa. The mission was a partial success. A sample mission to Earth’s sister planet is the holy-grail for the exploration of Venus. Image credit: JAXA

The 2003 Planetary Science Decadal Survey identified the importance of a sample return mission to Venus’ atmosphere. A balloon would float aloft in the clouds, and an ascending rocket would launch a collected sample back to Earth. According to Cutts and his team, this kind of sample-return mission could act as a stepping stone to a surface sample mission.

A surface sample would likely be the pinnacle of achievement when it comes to understanding Venus. But like most of the proposed goals for Venus, we’ll have to wait awhile.

The Changing Future

Cutts and the team acknowledge that the technology to enable exploration of Venus is in flux. No more missions to Venus are planned before 2020. There’ve been proposals for things like sail powered landers, but we’re not there yet. We’re developing heat-resistant electronics, but so far they’re very simple. There’s a lot of work to do.

On the other hand, some things may happen sooner. It may turn out that we can learn about Venusian seismic activity from balloon-borne or orbital sensors. The team says that “Due to strong mechanical coupling between the atmosphere and ground, seismic waves are launched into the atmosphere, where they may be detected by infrasound on a balloon or infrared or ultraviolet signatures from orbit.” That’s thanks to Venus’ dense atmosphere. That means that the far-term goal of seismic sensing of the interior of Venus could be shifted to the near-term or mid-term.

Japan’s Akatsuki orbiter captured this image of a gravity wave in Venus’ upper cloud layer. Could orbiter sensors remove the need for a network of seismic sensors on the surface? Image credit: JAXA

As work on nanosatellites and cubesats continues, they may play a larger role at Venus, and shift the timelines. NASA wants to include these small satellites on every launch where there is a few kilograms of excess capacity. A group of these nanosatellites could form a network of seismic sensors much more easily and much sooner than an established network of surface sensors. A network of nanosatellites could also serve as a communications relay for other missions.

Venus doesn’t generate a lot of buzz these days. The discovery of Earth-like worlds in distant solar systems generates headline after headline. And the always popular search for life is centered on Mars, and the icy/sub-surface moons of our Solar System’s gas giants. But Venus is still a tantalizing target, and understanding Venus’ evolution will help us understand what we’re seeing in distant solar systems.

February 10, 2017February 15, 2017 by Evan Gough

Time To Build A Venus Rover

The planet Venus, as imaged by the Magellan 10 mission. Credit: NASA/JPL — The planet Venus, as imaged by the Magellan 10 mission. The planet's inhospitable surface makes exploration extremely difficult. Credit: NASA/JPL

Venus is often described as being hell itself, because of its crushing pressure, acidic atmosphere, and extremely high temperatures. Dealing with any one of these is a significant challenge when it comes to exploring Venus. Dealing with all three is extremely daunting, as the Soviet Union discovered with their Venera landers.

Actually, dealing with the sulphuric rain is not too difficult, but the heat and the pressure on the surface of Venus are huge hurdles to exploring the planet. NASA has been working on the Venus problem, trying to develop electronics that can survive long enough to do useful science. And it looks like they’re making huge progress.

Scientists at the NASA Glenn Research Centre have demonstrated electronic circuitry that should help open up the surface of Venus to exploration.

The first color pictures taken of the surface of Venus by the Venera-13 space probe. Credit: NASA — The first color pictures taken of the surface of Venus by the Venera-13 space probe. The Venera 13 probe lasted only 127 minutes before succumbing to Venus’s extreme surface environment. Credit: NASA

“With further technology development, such electronics could drastically improve Venus lander designs and mission concepts, enabling the first long-duration missions to the surface of Venus,” said Phil Neudeck, lead electronics engineer for this work.

With our current technology, landers can only withstand surface conditions on Venus for a few hours. You can’t do much science in a few hours, especially when weighed against the mission cost. So increasing the survivability of a Venus lander is crucial.

With a temperature of 460 degrees Celsius (860 degrees Fahrenheit), Venus is almost twice as hot as most ovens. It’s hot enough to melt lead, in fact. Not only that, but the surface pressure on Venus is about 90 times greater than Earth’s, because the atmosphere is so dense.

To protect the electronics on previous Venus landers, they have been contained inside special vessels designed to withstand the pressure and temperature. But these vessels add a lot of mass to the mission, and make sending landers to Venus a very expensive proposition. So NASA’s work on robust electronics is super important when it comes to exploring Venus.

The team at the Glenn Research Centre has developed silicon carbide semiconductor integrated circuits (Si C IC) that are extremely robust. Two of the circuits were tested inside a special chamber designed to precisely reproduce the conditions on Venus. This chamber is called the Glenn Extreme Environments Rig (GEER.)

The GEER (Glenn Extreme Environments Rig) facility can recreate the conditions of any body in our Solar System. (No, not the Sun, obviously.) Image: NASA/Glenn Research Centre

GEER is a special chamber that can recreate the conditions on any body in our Solar System. It’s an 800 Litre (28 cubic foot) chamber that can simulate temperatures up to 500° C (932° F), and pressures from near-vacuum to over 90 times the surface pressure of Earth. GEER can also simulate exotic atmospheres with its precision gas-mixing capabilities. It can mix very specific quantities of gases down to parts per million accuracy. For these tests, that means the unit had to reproduce an accurate recipe of CO2, N2, SO2, HF, HCl, CO, OCS, H2S, and H2O, down to very tiny quantities. And the tests were a success.

“We demonstrated vastly longer electrical operation with chips directly exposed — no cooling and no protective chip packaging — to a high-fidelity physical and chemical reproduction of Venus’ surface atmosphere,” Neudeck said. “And both integrated circuits still worked after the end of the test.”

In fact, the two circuits not only functioned after the test was completed, but they withstood Venus-like conditions for 521 hours. That’s more than 100 times longer than previous demonstrations of electronics designed for Venus missions.

A before (top) and after (bottom) image of the electronics after being tested in Venus atmospheric conditions. Image: NASA

The circuits themselves were originally designed to operate in the extremely high temperatures inside aircraft engines. “This work not only enables the potential for new science in extended Venus surface and other planetary exploration, but it also has potentially significant impact for a range of Earth relevant applications, such as in aircraft engines to enable new capabilities, improve operations, and reduce emissions,” said Gary Hunter, principle investigator for Venus surface electronics development.”

The chips themselves were very simple. They weren’t prototypes of any specific electronics that would be equipped on a Venus lander. What these tests showed is that the new Silicon Carbide Integrated Circuits (Si C IC) can withstand the conditions on Venus.

A host of other challenges remains when it comes to the overall success of a Venus lander. All of the equipment that has to operate there, like sensors, drills, and atmospheric samplers, still has to survive the thermal expansion from exposure to extremely high temperature. Robust new designs will be required in many cases. But this successful test of electronics that can survive without bulky, heavy, protective enclosures is definitely a leap forward.

If you’re interested in what a Venus lander might look like, check out the Venus Sail Rover concept.

February 7, 2017February 6, 2017 by Matt Williams

How Long is a Day on Venus?

Venus is often referred to as “Earth’s Sister” planet, because of the various things they have in common. For example, both planets reside within our Sun’s habitable zone (aka. “Goldilocks Zone“). In addition, Earth and Venus are also terrestrial planets, meaning they are primarily composed of metals and silicate rock that are differentiated between a metallic core and a silicate mantle and crust.

Beyond that, Earth and Venus could not be more different. And two ways in which they are in stark contrast is the time it takes for the Sun to rise, set, and return to the same place in the sky (i.e. one day). In Earth’s case, this process takes a full 24 hours. But in Venus’ case, its slow rotation and orbit mean that a single day lasts as long as 116.75 Earth days.

Sidereal Vs. Solar:

Naturally, some clarification is necessary when addressing the question of how long a day lasts. For starters, one must distinguish between a sidereal day and a solar day. A sidereal day is the time it takes for a planet to complete a single rotation on its axis. On the other hand, a solar day is the time it takes for the Sun to return to the same place in the sky.

On Earth, a sidereal days last 23 hours 56 minutes and 4.1 seconds, whereas a solar day lasts exactly 24 hours. In Venus’ case, it takes a whopping 243.025 days for the planet to rotate once on its axis – which is the longest rotational period of any planet in the Solar System. In addition, it rotates in the opposite the direction in which it orbits around the Sun (which it takes about 224.7 Earth days to complete).

In other words, Venus has a retrograde rotation, which means that if you could view the planet from above its northern polar region, it would be seen to rotate in a clockwise direction on its axis, and in a counter-clockwise direction around the Sun. It also means that if you could stand on the surface of Venus, the Sun would rise in the west and set in the east.

From all this, one might assume that a single day lasts longer than a year on Venus. But again, the distinction between a sidereal and solar days means that this is not true. Combined with its orbital period, the time it takes for the Sun to return to the same point in the sky works out to 116.75 Earth days, which is little more than a half a Venusian (or Cytherian) year.

*At a closest average distance of 41 million km (25,476,219 mi), Venus is the closest planet to Earth. Credit: NASA/JPL/Magellan*

Axial Tilt and Temperatures:

Unlike Earth or Mars, Venus has a very low axial tilt – just 2.64° relative to the ecliptic. In fact, it’s axial tilt is the one of the lowest in the Solar System, second only to Mercury (which has an extremely low tilt of 0.03°). Combined with its slow rotational period and dense atmosphere, this results in the planet being effectively isothermal, with virtually no variation in its surface temperature.

In other words, the planet experiences a mean temperature of 735 K (462 °C; 863.6 °F) – the hottest in the Solar System – with very little change between day and night, or between the equator and the poles. In addition, the planet experiences minimal seasonal temperature variation, with the only appreciable variations occurring with altitude.

Weather Patterns:

It is a well-known fact that Venus’ atmosphere is incredibly dense. In fact, the mass of Venus atmosphere is 93 times that of Earth’s, and the air pressure at the surface is estimated to be as high as 92 bar – i.e. 92 times that of Earth’s at sea level. If it were possible for a human being to stand on the surface of Venus, they would be crushed by the atmosphere.

The composition of the atmosphere is extremely toxic, consisting primarily of carbon dioxide (96.5%) with small amounts of nitrogen (3.5%) and traces of other gases – most notably sulfur dioxide. Combined with its density, the composition generates the strongest greenhouse effect of any planet in the Solar System.

According to multiple Earth-based surveys and space missions to Venus, scientists have learned that its weather is rather extreme. The entire atmosphere of the planet circulates around quickly, with winds reaching speeds of up to 85 m/s (300 km/h; 186.4 mph) at the cloud tops, which circle the planet every four to five Earth days.

At this speed, these winds move up to 60 times the speed of the planet’s rotation, whereas Earth’s fastest winds are only 10-20% of the planet’s rotational speed. Spacecraft equipped with ultraviolet imaging instruments are able to observe the cloud motion around Venus, and see how it moves at different layers of the atmosphere. The winds blow in a retrograde direction, and are the fastest near the poles.

Closer to the equator, the wind speeds die down to almost nothing. Because of the thick atmosphere, the winds move much slower as you get close to the surface of Venus, reaching speeds of about 5 km/h. Because it’s so thick, though, the atmosphere is more like water currents than blowing wind at the surface, so it is still capable of blowing dust around and moving small rocks across the surface of Venus.

Venus flybys have also indicated that its dense clouds are capable of producing lightning, much like the clouds on Earth. Their intermittent appearance indicates a pattern associated with weather activity, and the lightning rate is at least half of that on Earth.

*Artist concept of the surface of Venus, showing its dense clouds and lightning storms. Credit: NASA*

Yes, Venus is a planet of extremes. Extreme heat, extreme weather, and extremely long days! In short, there’s a reason why nobody lives there. But who knows? Given the right kind of technology, and perhaps even some dedicated terraforming efforts, people could one day being watching the Sun rising in the west and setting in the east.

We have written many interesting articles about Venus here at Universe Today. Here’s Venus compared to Earth, How Fast Does Venus Rotate?, What is the Weather Like on Venus?, How Long is a Year on Venus?, What is the Average Surface Temperature on Venus?, and How Long is a Day on the Other Planets of the Solar System?

For more information, check out NASA’s Solar System Exploration page on Venus.

Astronomy Cast also has a good episodes on the subject. Here’s Episode 50: Venus

Sources:

January 11, 2017 by David Dickinson

Venus Rules the Dusk Skies at Greatest Elongation

Venus at dusk — Venus, Mars, and the waxing crescent moon at dusk from the evening of January 3rd, 2017. Image credit and copyright: Alan Dyer.

“What’s that bright light in the sky?” The planet Venus never fails to impress, and indeed makes even seasoned observers look twice at its unexpected brilliance. The third brightest natural object in the sky, Venus now rules the dusk, a fine sight for wintertime evening commuters. Venus reaches greatest elongation tomorrow, a excellent time to admire this dazzling but shrouded world of mystery.

Venus at greatest elongation

Only the two planets interior to Earth’s orbit – Mercury and Venus – can reach a point known as greatest elongation from the Sun. As the name suggests, this is simply the point at which either planet appears to be at its maximum angular distance from the Sun. Think of a big right triangle in space, with Venus or Mercury at the right angle vertex, and the Sun and Earth at the other two corners. High school geometry can come in handy!

Venus elongation — Venus at greatest elongation (planets and orbits not to scale). Credit: Dave Dickinson

This Thursday on January 12^th Venus reaches a maximum of 47 degrees elongation from the Sun at 11:00 Universal Time (UT) / 6:00 AM Eastern Standard Time, shining at magnitude -4.4. The maximum/minimum elongation for Venus that can occur is 47.3 to 45.4 degrees respectively, and this week’s is the widest until 2025.

Here’s some key dates to watch out for:

Jan 12^th: Venus passes less than a degree from Neptune.

Jan 14^th: Venus reaches theoretical dichotomy?

Jan 14^th: Venus passes 3′ from +3.7 the magnitude star Lambda Aquarii.

Jan 17^th: Venus crosses the ecliptic plane northward.

Venus and Mars reach ‘quasi-conjunction’ in late January.

January 30^th: Venus crosses the celestial equator northward.

January 31^st: The Moon passes 4 degrees south of Venus, and the two also form a nice equilateral triangle with Mars on the same date.

Looking west on the evening of January 31st, 2017. Image credit: Stellarium.

February 17^th: Venus reaches a maximum brilliancy of magnitude -4.6.

March 26^th: Solar conjunction for Venus occurs eight degrees north of the Sun … it is possible to spy Venus at solar conjunction from high northern latitudes, just be sure to block out the Sun.

Through the telescope, Venus displays a tiny 24.4” size half phase right around greatest elongation. You could stack 74 Venuses across the diameter of tomorrow’s Full Moon. When does Venus look to reach an exact half phase to you? This point, known as theoretical dichotomy, is often off by just a few days. This is a curious observed phenomenon, first noted by German amateur astronomer Johann Schröter in 1793. The effect now bears his name. A result of atmospheric refraction along the day/terminator on Venus, or an optical illusion?

Gibbous Venus — Almost there… a waning gibbous Venus from the evening of January 5th, 2017. Image credit and copyright: Shahrin Ahmad (@Shahgazer)

And hey, amateurs are now using ultraviolet filters to get actual detail on the cloud-tops of Venus… we like to use a variable polarizing filter to cut down the dazzling glare of Venus a bit at the eyepiece.

Also, keep an eye out for another strange phenomenon, known as the Ashen Light of Venus. Now,ashen light or Earthshine is readily apparent on dark side of the Moon, owing to the presence of a large sunlight reflector nearby, namely the Earth. Venus has no such large partner, though astronomers in the early age of telescopic astronomy claimed to have spied a moon of Venus, and even went as far as naming it Neith. An optical illusion? Or real evidence of Venusian sky glow on its nighttime side? After tomorrow, Venus will begin heading between the Earth and the Sun, becoming a slender crescent in the process. Solar conjunction occurs on March 25^th, 2017. Venus sits just eight degrees north of the Sun on this date, and viewers in high Arctic latitudes might just be able to spy Venus above the horizon before sunrise on the day of solar conjunction. We performed a similar feat of visual athletics on the morning of January 16^th, 1998 observing from North Pole, Alaska.

Venus as seen from Fairbanks, Alaska on the morning of solar conjunction, 2017. Image credit: Starry Night.

From there, Venus heads towards a fine dawn elongation on June 3^rd, 2017. All of these events and more are detailed in our free e-book: 101 Astronomical Events for 2017.

Spying Venus in the Daytime

Did you know: you can actually see Venus in the daytime, if you know exactly where to look for it? A deep blue, high contrast sky is the key, and a nearby crescent Moon is handy in your daytime quest. Strange but true fact: Venus is actually brighter than the Moon per square arc second, with a shiny albedo of 70% versus the Moon’s paltry 12%. But Venus is tiny, and hard to spot against the blue daytime sky… until you catch sight of it.

The Moon passing Venus on January 31st, 2017 in the daytime sky. Image credit: Stellarium.

There’s another reason to brave the January cold for northern hemisphere residents: Venus can indeed cast a shadow if you look carefully for it. You’ll need to be away from any other light sources (including the Moon, which passes Full tomorrow as well with the first Full Moon of 2017, known as a Full Wolf Moon). And a high contrast surface such as freshly fallen snow can help… a short time exposure shot can even bring the shadow cast by Venus into focus.

If you follow Venus long enough, you’ll notice a pattern, as it visits very nearly the the same sky environs every eight years and traces out approximately the same path in the dawn and dusk sky. There’s a reason for this: 8 Earth years (8x 365.25 = 2922 days) very nearly equals 5 the synodic periods for Venus (2922/5=584 days, the number of days it takes Venus to return to roughly the same point with respect to the starry background, separate from its true orbit around the Sun of 225 days). For example, Venus last crossed the Pleiades star cluster in 2012, and will do so again in – you guessed it — in 2020. Unfortunately, this pattern isn’t precise, and Venus won’t also transit the Sun again in 2020 like it did in 2012. You’ll have to wait until one century from this year on December 10-11^th, 2117 to see that celestial spectacle again….

Hopefully, we’ll have perfected that whole Futurama head-in-a-jar thing by then.

November 1, 2016November 4, 2016 by Bob King

November Opens with a Splendid Gathering of Moon and Planets

Crescent Moon and flag. Credit: Bob King

Look how pretty. This will be the scene from your yard, apartment window or driving west along the freeway Tuesday evening about 45 minutes after sundown. Saturn and the Moon will be in conjunction about 3 degrees apart with Venus 6 degrees to the southeast of the crescent. Source: Stellarium — Look how pretty. This will be the scene from your yard, apartment window or driving west along a freeway Tuesday evening about 45 minutes after sundown. Saturn and the Moon will be in conjunction about 3 degrees apart with Venus 6 degrees to the southeast of the crescent. Source: Stellarium

I love easy and bright. While I often spend time seeking faint nebulae and wandering comets, there’s nothing like just looking up and seeing a beautiful scene aglow in the night sky. No binoculars or telescope needed. That’s exactly what will happen Tuesday November 2, when an attractive crescent Moon will join Saturn and Venus at dusk in the southwestern sky.

The supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). Note the size difference. Image Credit: Marco Langbroek, the Netherlands, via Wikimedia Commons. — The Supermoon of March 19, 2011 (right), compared to an average moon of December 20, 2010 (left). November’s Supermoon will be 14% bigger and 30% brighter than a regular Full Moon. Credit: Marco Langbroek / Wikimedia Commons

What a fine threesome they’ll make: Venus the white-hot spark shining at magnitude –4.0; Saturn a mellow magnitude +0.5, some 20 times fainter and the Moon a fingernail crescent above them both. The Moon will be just two days past apogee, the furthest point in its orbit from Earth. Does it look a little smaller than the usual crescent? If you’re a keen watcher of crescents, you just might notice the difference.

In less than two weeks, on November 14, the crescent will have waxed to full, swung around to the opposite end of its orbit, where it will be at perigee, its closest point to Earth. When a Full Moon occurs at perigee, we call it a Supermoon because it’s closer and correspondingly bigger and brighter than a typical Full Moon.

For a variety of reasons, the November Supermoon will come exceptionally close to Earth, the closest one in 70 years as a matter of fact. The last time Earth and Moon embraced each other so tightly was January 26, 1948, the year baseball great Babe Ruth died. But I’m getting ahead of myself. We’ll have much more on the Supermoon soon!

This photo shows the contrast between the bright, sunlit crescent and the ghostly earth-lit Moon. Several prominent craters are identified. Credit: Bob King

Tuesday night you have the pleasure of an eye-catching crescent filled with darkly luminous earthshine, sunlight reflected off our jolly blue and white globe into space that reflects from the Moon and back to Earth. Being twice reflected, the returning light is feeble, giving the Moon a haunted look.

The phases of the Moon and Earth are complementary; when one's a crescent, the other's nearly full. Credit: Bob King, Source: Stellarium — The phases of the Moon and Earth are complementary; when one’s a crescent, the other’s nearly full. Credit: Bob King, Source: Stellarium

Crescent phase is when earthshine is brightest. Why? Phases of Earth and Moon are complementary — when we see a crescent, an astronaut on the Moon would look back to see a nearly Full Earth in the sky. As you’ve already guessed, a Full Earth reflects a great deal more light than a half or crescent. Be sure to point your binoculars at the earth-lit Moon; the contrast of dusky earthlight adjacent to the sunlit crescent gives the scene a striking 3D look.

And if your glass can magnify ten times or more, you’ll get a sneak preview of several of the dark lunar seas or maria in the smoky light. Seas that will by and by ease into sunlight as the lunar terminator, the line separating day from night, rolls ever westward.

Through a small telescope, Venus appears three-quarters full in waning gibbous phase. Saturn's rings are still tipped wide open, and it's brightest moon, Titan, should be easy to spot Tuesday night in a small telescope. Source: Stellarium — Through a small telescope, Venus appears three-quarters full in waning gibbous phase. Saturn’s rings are still tipped wide open, and its brightest moon, Titan, should be easy to spot Tuesday night in a small telescope. Appearances are shown for Nov. 2. North is up and west to the right. Source: Stellarium

Have a small telescope? This may be one of your last easy chances at seeing the planet Saturn before it’s gobbled up by the western horizon. The ringed one has been sinking westward the past couple months and will soon be in conjunction with the Sun. I hate to see a good planet go, that’s why I’m happy to share that Venus will be with us a long, long time. Watch for this most brilliant of planets to rise higher in the southwestern sky as we approach Christmas and then swing to the north through early winter before dropping out of the evening sky in March 2017.

Thank you Venus for lighting our path on the snowy nights that lie ahead!

*** If you’d like learn more about how to find the planets, check out my new book, Night Sky with the Naked Eye. It covers all the wonderful things you can see in the night sky without special equipment. The book publishes on Nov. 8, but you can pre-order it right now at these online stores. Just click an icon to go to the site of your choice – Amazon, Barnes & Noble or Indiebound. It’s currently available at the first two outlets for a very nice discount:

October 20, 2016 by Evan Gough

No, There Won’t Be 15 Days of Darkness in November. It’s Another Stupid Hoax.

Venus and Jupiter at dusk over Australia's Outback on June 27, 2015. Credit: Joseph Brimacombe

The internet is great, isn’t it?

You can post anything you want on the internet, and if people like the sound of it, they spread it. It doesn’t make any difference if it’s true or not. We’re not born fact checkers and skeptics, are we?

Pretty soon, before you know it, it’s gone viral. Then it becomes its own sensation, and people who don’t even believe it start reporting it. Never is this more true than with hoaxes.

The latest hoax is the “15 Days of Darkness in November” thing that’s going around. Everyone’s on the bandwagon.

The 15 days hoax is not new. It made an appearance last year, and was thoroughly debunked. And of course, there wasn’t 15 day of darkness last year, was there? (Unless NASA covered it up!)

It’s here again this year, and will be debunked again, and will probably be here next year, too.

The whole thing started at a site that will remain linkless, and caught on from there. This is what the site reported:

“NASA has confirmed that the Earth will experience 15 days of total darkness between November 15 and November 29, 2015. The event, according to NASA, hasn’t occurred in over 1 Million years.”

Of course, NASA never said any such thing.

Here is supposedly what will happen to cause this calamity. Try and follow along with the nonsensical foolishness.

During the conjunction between Venus and Jupiter on October 26, light from Venus would cause gases in Jupiter to heat up. The heated gasses will cause a large amount of hydrogen to be released into space. The gases will reach the Sun and trigger a massive explosion on the surface of the star, heating it to 9,000 degrees Kelvin. The heat of the explosion would then cause the Sun to emit a blue color.
The dull blue color will last for 15 days during which the Earth will be thrown into darkness.

Where to begin? Let’s start with conjunctions.

Conjunctions are mostly just visual phenomena. The fact that two things in the sky look closer together from our point of view on Earth doesn’t mean that they’re that close together. In fact, even when Jupiter and Venus are in conjunction, they can still be over 800 million km apart. For perspective, the Sun and the Earth are about 150 million km apart.

So, as the hoax goes, at that great distance, light from Venus will cause gases on Jupiter to heat up. News Flash: the light from the Sun is far more intense than light from Venus could ever be, and it doesn’t heat up the gases on Jupiter. In fact, any light from Venus that makes it to Jupiter is just reflected sunlight anyway.

The Moon and this dead tree are in conjunction. This will cause the Martian Pyramids to vibrate harmonically. These vibrations will shake the walls of the movie studio where the Moon landing was faked, causing it to collapse. Image: Evan Gough

The hoax gets more outrageous as it goes along. These supposed heated gases then escape from Jupiter into space, and head for the Sun. But Jupiter is enormous and has enormous gravitational pull. How are any gases going to escape Jupiter’s overpowering gravity? Answer: they can’t and they won’t.

Then, these gases supposedly strike the Sun, and trigger a massive explosion on the Sun’s surface, which turn the Sun blue and plunges the Earth into darkness. Not blueness, which I could understand, but darkness.

This is absurd, of course. The Sun dominates the planets in a one-way relationship, and nothing the planets ever do could change that. No escaped gases from Jupiter would ever strike the Sun.

Jupiter is puny and insignificant compared to the Sun. And it's also hundreds of millions of kilometers away. How is a puny puff of hydrogen from Jupiter supposed to darken the Sun? Image: NASA/SDO — Jupiter is puny and insignificant compared to the Sun. And it’s also hundreds of millions of kilometers away. How is a puny puff of hydrogen from Jupiter supposed to darken the Sun? Image: NASA/SDO

Nothing Jupiter does can affect the Sun. Jupiter is, on average, 778 million km from the Sun. Jupiter could change places with Venus, and the Sun would keep shining normally. Jupiter could explode completely and the Sun would go on shining normally. Jupiter could put on a big red nose and some clown shoes, and the Sun would remain unaffected.

The Sun is a giant atom-crushing machine 1000 times more massive than Jupiter. The massive wall of energy and solar wind that comes from the Sun slams into Jupiter, and completely overwhelms anything Jupiter can do to the Sun. It’s just the way it is. It’s just the way it will always be.

Like the faked Moon landing hoax, and the Nibiru/Planet X hoax, this 15 days of darkness meme just keeps coming around. There may be no end to it.

It’s annoying, for sure, but maybe there’s a silver lining. Maybe some people reading about this supposed calamity will enter the word “conjunction” into a search engine, and begin their own personal journey of learning how the universe works.

We can hope so, can’t we?

October 11, 2016November 5, 2016 by Matt Williams

X-Rays Are Coming From The Dark Side of Venus

On June 5th, 2012, the NASA/JAXA Hinode mission captured these stunning views of the transit of Venus. Credit: JAXA/NASA/Lockheed Martin

Venus and Mercury have been observed transiting the Sun many times over the past few centuries. When these planets are seen passing between the Sun and the Earth, opportunities exist for some great viewing, not to mention serious research. And whereas Mercury makes transits with greater frequency (three times since 2000), a transit of Venus is something of a rare treat.

In June of 2012, Venus made its most recent transit – an event which will not happen again until 2117. Luckily, during this latest event, scientists made some very interesting observations which revealed X-ray and ultraviolet emissions coming from the dark side of Venus. This finding could tell us much about Venus’ magnetic environment, and also help in the study of exoplanets as well.

For the sake of their study (titled “X-raying the Dark Side of Venus“) the team of scientists – led by Masoud Afshari of the University of Palermo and the National Institute of Astrophysics (INAF) – examined data obtained by the x-ray telescope aboard the Hinode (Solar-B) mission, which had been used to observe the Sun and Venus during the 2012 transit.

Artist's impression of the Hinode (Solar-B) spacecraft in orbit. Credit: NASA/GSFC/C. Meaney — *Artist’s impression of the Hinode (Solar-B) spacecraft in orbit. Credit: NASA/GSFC/C. Meaney*

In a previous study, scientists from the University of Palermo used this data to get truly accurate estimates of Venus’ diameter in the X-ray band. What they observed was that in the visible, UV, and soft X-ray bands, Venus’ optical radius (taking into account its atmosphere) was 80 km larger than its solid body radius. But when observing it in the extreme ultraviolet (EUV) and soft X-ray band, the radius increased by another 70 km.

To determine the cause of this, Afshari and his team combined updated information from Hinode’s x-ray telescope with data obtained by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory (SDO). From this, they concluded that the EUV and X-ray emissions were not the result of a fault within the telescope, and were in fact coming from the dark side of Venus itself.

They also compared the data to observations made by the Chandra X-ray Observatory of Venus in 2001 and again in 2006-7m which showed similar emissions coming from the sunlit side of Venus. In all cases, it seemed clear that Venus had unexplained source of non-visible light coming from its atmosphere, a phenomena which could not be chalked up to scattering caused by the instruments themselves.

Comparing all these observations, the team came up with an interesting conclusion. As they state in their study:

“The effect we are observing could be due to scattering or re-emission occurring in the shadow or wake of Venus. One possibility is due to the very long magnetotail of Venus, ablated by the solar wind and known to reach Earth’s orbit… The emission we observe would be the reemitted radiation integrated along the magnetotail.”

On June 5-6 2012, NASA's Solar Dynamics Observatory, or SDO, collected images of one of the rarest predictable solar events: the transit of Venus across the face of the sun. This event happens in pairs eight years apart that are separated from each other by 105 or 121 years. The last transit was in 2004 and the next will not happen until 2117. Credit: NASA/SDO, AIA — *Collected images of Venus 2012 transit of the Sun, taken in June of 2012 by NASA’s Solar Dynamics Observatory (SDO). Credit: NASA/SDO, AIA*

In other words, they postulate that the radiation observed emanating from Venus could be due to solar radiation interacting with Venus’ magnetic field and being scattered along its tail. This would explain why from various studies, the radiation appeared to be coming from Venus’ itself, thus extending and adding optical thickness to its atmosphere.

If true, this finding would not only help us to learn more about Venus’ magnetic environment and assist our exploration of the planet, it would also improve our understanding of exoplanets. For example, many Jupiter-sized planets have been observed orbiting close to their suns (i.e. “Hot Jupiters“). By studying their tails, astronomers may come to learn much about these planets’ magnetic fields (and whether or not they have one).

Afshari and his colleagues hope to conduct future studies to learn more about this phenomenon. And as more exoplanet-hunting missions (like TESS and the James Webb Telescope) get underway, these newfound observations of Venus will likely be put to good use – determining the magnetic environment of distant planets.

Further Reading: The Astronomical Journal

August 22, 2016 by Bob King

5 Days, 2 Spectacular Conjunctions

Two planets close and up close. This is the view through a telescope during the extremely close conjunction of Jupiter and Venus on August 27. Credit: Stellarium

Saturn, Mars and Antares are shown on Sunday night August 21 two nights before their lineup. Mars is still far and away the brightest object in the bunch at magnitude -0.5. Details: 35mm lens, f/2.8, ISO 400, 10 seconds. Credit: Bob King — Saturn, Mars and Antares are shown on Sunday night August 21 two nights before their lineup. Mars is still the brightest of the bunch at magnitude –0.5. It will with Saturn at +0.4 and Antares at +1.0. Details: 35mm lens, f/2.8, ISO 400, 10 seconds. Credit: Bob King

Conjunctions of bright planets make for jewelry in the sky. This week, get ready for some celestial shimmer. If you’ve been following the hither and thither of Mars and Saturn near Antares this summer, you know these planets have been constantly on the move, creating all kinds of cool alignments in the southern sky.

On Tuesday night (August 23) the hopscotching duo will fall in line atop Antares in the southwestern sky at nightfall. Mars will sit just 1.5° above the star and Saturn 4° above Mars. Viewed from the Americas and Europe, the line will appear slightly bent. To catch them perfectly lined up, you’ll have to be in central Asia on the following evening, but the view should be pleasing no matter where you live.

This will be the scene facing south at nightfall from the central U.S. on Tuesday night August 23. The two planets and star form a compact gathering that's sure to grab your attention. Credit: Stellarium — This will be the scene facing southwest at nightfall from the central U.S. on Tuesday night August 23. The two planets and star form a compact gathering that’s sure to grab your attention. The moment of conjunction between Mars and Saturn occurs at 11:00 UT (7 a.m. Eastern Aug. 24), but they’ll be below the horizon at that time for the Americas and Europe. Credit: Stellarium

Nice as it is, the Mars-Saturn-Antares lineup is only the warm-up for the big event: the closest conjunction of the two brightest planets this year. On Saturday evening, August 27, Venus and Jupiter will approach within a hair’s breadth of each other as viewed with the naked eye — only 0.1° will separate the two gems. That’s one-fifth of a full moon’s width! While Mars and Saturn will be a snap to spot low in the southwestern sky during their conjunction, Venus and Jupiter snuggle near the western horizon at dusk.

Look for Venus and Jupiter right next to each other 4 degrees (about three fingers held together horizontally) above the western horizon about a half-hour after sunset on August 27. Map: Bob King; source: Stellarium — Look for Venus and Jupiter right next to each other 4° (about three fingers held together horizontally) above the western horizon about a half-hour after sunset on August 27. This map shows the view from across the central U.S. at about 40°N latitude. The two planets will be closest at 22:00 UT (6 p.m. Eastern, 7 p.m. Central, 8 p.m. Mountain and 9 p.m. Pacific). Map: Bob King; source: Stellarium

To make sure you see them, find a place in advance of the date with a wide open view to the west. I also suggest bringing a pair of binoculars. It’s so much easier to find an object in bright twilight with help from the glass. You can start looking about 25 minutes after sunset; Venus will catch your eye first. Once you’ve found it, look a smidge to its lower right for Jupiter. If you’re using binoculars, lower them to see how remarkably close the two planets appear using nothing but your eyeballs. Perhaps they’ll remind you of a bright double star in a telescope or even the twin suns of Tatooine in Star Wars.

Here's what the two planets will look like through a telescope at medium and high magnification, when both will comfortably fit into the same field of view. Stellarium — The two planets will be only 6 arc minutes apart Saturday evening and easily fit in the same field of view of a telescope at high magnification. Jupiter’s four brightest moons will be obvious. If you’re patient and wait for the air to settle, you’ll be able to make out Venus’s waxing gibbous phase. Credit: Stellarium

Have a small telescope? Take it along — Jupiter and Venus are so close together that they easily fit in the same high magnification field of view. Jupiter’s four brightest moons will be on display, and Venus will look just like a miniature version of the waxing gibbous moon. Rarely do the sky’s two brightest planets nearly fuse, making this a not-to-miss event.

Venus and Jupiter do a little square dance over the nights of August 26-28. Jupiter is headed westward toward conjunction with the sun, while Venus is moving away from the sun from our perspective. Stellarium — Venus and Jupiter do a little square dance over the nights of August 26-28. Jupiter is headed westward toward conjunction with the sun, while Venus is moving away from the sun in the opposite direction from our perspective. Credit: Stellarium

If cloudy weather’s in the forecast that night, you can still spot them relatively close together the night before and night after, when they’ll be about 1° or two full moon diameters apart. I get pretty jazzed when bright objects approach closely in the sky, and I’m betting you do, too.

I also don’t mind being taken in by illusion once in a while. During a conjunction, planets only appear close together because we view them along the same line of sight. Their real distances add a dose of reality.

On Saturday evening Venus will be 143 million miles (230 million km) away vs. 592 million miles (953 million km) for Jupiter. In spite of appearing to almost touch, Jupiter is more than four times farther than the goddess planet.

The showpieces in this week's conjunction parade: Jupiter, Venus, Mars and Saturn. Credit: NASA/ESA — The showpieces in this week’s conjunction parade: Jupiter, Venus, Mars and Saturn. Credit: NASA/ESA

That distance translates to the chill realm of the giant gaseous planets where sunlight is weak and ice is common. Try stretching your imagination that evening to sense as best you can the vast gulf between the two worlds.

You might also try taking a picture of them with your mobile phone. I suggest this because the sky will be light enough to get a hand-held photo of the scene. Photos or not, don’t miss what the planets have in store for earthlings this week.

March 30, 2016 by David Dickinson

A Challenging Daytime Occultation of Venus for Europe

Do you see it? I 2% illuminated waning 'Old Moon,' 24+ hours from New. The April 6th Moon will be about as thin. Image credit: Dave Dickinson

Sometimes, the Universe seems bent on hiding the most glorious of events right in plain sight. Just a such an event occurs next week, when the slender waning crescent Moon occults the planet Venus for observers across Europe, the United Kingdom and northern Asia. Continue reading “A Challenging Daytime Occultation of Venus for Europe”

March 2, 2016March 18, 2016 by Evan Gough

Venus: 50 Years Since Our First Trip, and We’re Going Back

The first spacecraft to reach the surface of another world was the Soviet Venera 3 probe. Venera 3 crash-landed on the surface of Venus on March 1, 1966, 50 years ago. It was the 3rd in the series of Venera probes, but the first two never made it.

Venera 3 didn’t last long. It survived Venus’ blistering heat and crushing atmospheric pressure for only 57 minutes. But because of that 57 minutes, its place in history is cemented.

With a temperature of 462 degree C. (863 F.,) and a surface pressure 90 times greater than Earth’s, Venus’ atmosphere is the most hostile one in the Solar System. But Venus is still a tantalizing target for exploration, and rather than letting the difficult conditions deter them, Venus is a target that NASA thinks it can hit.

The Venus Landsail—called Zephyr—could be the first craft to survive the hostile environment on Venus. If approved, it would launch in 2023, and spend 50 days on the surface of Venus. But to do so, it has to meet several challenges.

NASA thinks they have the electronics that can withstand the heat, pressure, and corrosive atmosphere of Venus. Their development of sensors that can function inside jet engines proves this, and is the kind of breakthrough that really helps to advance space exploration. They also have solar cells that should function on the surface of Venus.

But the thick cloud cover will prevent the Zephyr’s solar cells from generating much electricity; certainly not enough for mobility. They needed another solution for traversing the surface of Venus: the land sail.

An artist's conception of what NASA's Zephyr Landsail might look like on the surface of Venus. Image: NASA Glenn Research Center. — An artist’s conception of what NASA’s Zephyr Landsail might look like on the surface of Venus. Image: NASA Glenn Research Center.

Venus has very slow winds—less than one meter per second—but the high density of the atmosphere means that even a slow wind will allow Zephyr to move effectively around the Venusian surface. But a land sail will only work on a surface without large rocks in the way. Thanks to the images of the surface of Venus sent back to Earth from the Venera probes, we know that a land sail will work, at least in some parts of the Venusian surface.

So Venus is back on the menu. With all the missions to other places in the Solar System, Venus is kind of forgotten, right here in our own backyard. But there’s actually a pretty rich history of missions to Venus, even though an extended visit to the surface has been out of reach. Since it’s been 50 years since Venera 3 reached the surface, now is a good time to look back at the history of the exploration of Venus.

The Soviet Union dominated the exploration of Venus. The Venera probes went all the way up to Venera 16, though some were orbiters rather than landers. From one perspective, the whole Venera program was plagued with problems. Many of the craft failed completely, or else had malfunctions that crippled them. But they still returned important information, and achieved many firsts, so the Venera program overall has to be considered a success.

The Soviet Union did not like to acknowledge or talk about space missions that failed. They often changed the name of a mission if it failed, so the names and numbers can get a little confusing.

Venera 4 was actually the first spacecraft to transmit any data from another world. On October 18th, 1967, it transmitted data from Venus’ atmosphere, but none from the surface. There were actually ten Venera missions before it, but most of them didn’t make it to Venus, suffering explosions or failing to leave Earth’s orbit and crashing back to the surface of Earth. Two of the Venera probes, numbers 1 and 2, suffered a loss of communications, so their fate is unknown.

After Venera 4’s relative success, there was another failed craft that fell back to Earth. Then on May 16th, 1969, Venera 5 successfully entered Venus’ atmosphere, and made it to within 26 kilometers of the surface before being crushed by the pressure. The next day—the Soviets often launched missions in pairs—Venera 6 entered the atmosphere of Venus and successfully transmitted data. It made it deeper into the atmosphere before being crushed within 11 kilometers of the surface.

Venera 7 was a successful mission. On December 15th, 1970, it landed on the surface of Venus and survived for 23 minutes. Venera 7 was the very first broadcast from the surface of another planet.

In 1972 Venera 8 survived for 50 minutes on the surface, followed by Venera 9 in 1975. Venera 9 survived for 53 minutes and sent back the first black and white images of the surface of Venus. Venera 10 landed 3 days after Venera 9 and survived 65 minutes, and also sent photos back. Grainy and blurry, but still amazing!

Images from Venera 9 (top) and Venera 10 (bottom). Public Domain Images, courtesy of NASA/National Space Science Data Center.

December 1978 saw the arrival of Venera 11 and 12, surviving 95 and 112 minutes respectively. Venera 11’s camera failed, but Venera 12 recorded what is thought to be lightning.

In March 1982, Venera 13 and 14 arrived. 13 took the first color images of the surface of Venus, and both craft took soil samples. Venera 15 and 16—both orbiters—arrived in 1983 and mapped the northern hemisphere.

The Soviet Unions final missions to Venus were Vega 1 and Vega 2, in 1985, which combined landings on Venus and flybys of Halley’s comet into each mission. Vega 1’s surface experiments failed, while Vega 2 transmitted data from the surface for 56 minutes.

The United States has also launched several mission to Venus, though none have been landers. Spacecraft in the Mariner series studied Venus from orbit and during flybys, sometimes getting quite close to the cloud tops.

In 1962 and 1967, Mariner 2 and 5 completed flybys of Venus and transmitted data back to Earth. Mariner 5 came as close as 4094 km of the surface. In February 1974, Mariner 10 approached Venus and came to within 5,768 km. It returned color images of Venus, and then used gravitational assist—the first spacecraft to ever do so—to propel itself to Mercury.

Mariner 10's Venus. Image: NASA — Mariner 10’s Venus. Image: NASA

In December 1978, the Pioneer Venus Orbiter reached Venus and studied the atmosphere, surface, and other aspects of Venus. It lasted until August 1992, when its fuel ran out and it was destroyed when it entered the atmosphere.

On August 1990, the Magellan mission reached Venus and used radar to map the surface of the planet. On October 1994, Magellan entered the Venusian atmosphere and was destroyed, but not before successfully mapping over 99% of the planet’s surface.

Deployment of Magellan with Inertial Upper Stage booster. Credit: NASA

Messenger was a NASA mission to Mercury that was launched in August 2004. It did two flybys of Venus, in October 2006 and June 2007.

The Venus Express, a European Space Agency mission, orbited Venus and studied the atmosphere and plasma of Venus. Of special interest to Venus Express was the study of what role greenhouse gases played in the formation of the atmosphere.

In 2010, the Japanese Space Agency launched Akatsuki, also known as the Venus Climate Orbiter. It’s role is to orbit Venus and study the atmospheric dynamics. It will also look for evidence of lightning and volcanic activity.

If there’s one thing that space exploration keeps teaching us, it’s to expect the unexpected. Who knows what we’ll find on Venus, if the Land Sail mission is approved, and it survives for its projected 50 days.