Venus rotation shortened for 6,5 minutes. What's causing the planet to slow down?

Venus rotation shortened for 6,5 minutes. What's causing the planet to slow down?

Using the VIRTIS instrument at infrared wavelengths to penetrate the thick cloud cover, scientists studied surface features and discovered that some were displaced by up to 20 km from where they should be given the accepted rotation rate as measured by NASA’s Magellan orbiter in the early 1990s. In the 1980s and 1990s, the Venera and Magellan orbiters made radar maps of the surface of Venus which  gave us first detailed global view of the planet.

Magellan's observations allowed scientists to determine the length of the day on Venus as being equal to 243.0185 Earth days. And 16 years later, ESA's Venus Express observed unusual situation - some surface features could only be lined up with those observed by Magellan if the length of the Venus day is on average 6.5 minutes longer than Magellan measured.

"When the two maps did not align, I first thought there was a mistake in my calculations as Magellan measured the value very accurately, but we have checked every possible error we could think of," said Nils Müller, a planetary scientist at the DLR German Aerospace Centre, lead author of a research paper investigating the rotation.



What could cause the planet to slow down? One possibility may be the raging weather on Venus. Earth experiences a similar effect, where it is largely caused by wind and tides. The length of an Earth day can change by roughly a millisecond and depends seasonally with wind patterns and temperatures over the course of a year.

But a change of 6.5 minutes over a little more than a decade is a huge variation.

Venus Express was able to peer at infrared wavelengths through the dense atmosphere and map surface features observed from both Earth-based radar imaging and with the Russian Venera 15 and 16 missions as well as NASA’s Magellan spacecraft. Topographic maps from Magellan and Venus Express show the shift in surface features. By comparing the currently accepted rotation rate value for the planet from the Magellan mission, scientists discovered a ‘shift’ in surface features of up to 20 km caused by what they believe is a change in the rotation rate of the planet. And the most recent long-duration radar measurements from Earth indicates the same situation.

Other recent atmospheric models have shown that the planet could have weather cycles stretching over decades, which could lead to equally long-term changes in the rotation period. Some scientists suggest that  exchanges of angular momentum between Venus and the Earth when the two planets are relatively close to each other could influence on current observed surface features.

The United States, Soviet Union, and European Space Agency have sent many spacecraft to Venus. Some flew by the planet, some orbited it, some descended through the atmosphere and struck the surface (hard-landed), and a few soft-landed on the surface. Future missions could include long-lived landers, specialized descent probes, aerobots (controllable balloons), and long-term orbital atmospheric monitoring satellites.

Venus Express will keep monitoring the planet to determine if the rate of rotation continues to change.



For those that are not so familiar with Venus and it's characteristic, we compiled some information for better understanding of the subject.

Introducing Venus

Venus has a similar size, mass, density and chemical composition as Earth. That's why its often called our "twin". Some even call it our "evil twin". Of course, its high temperatures and extreme atmospheric pressure (93 bar or 9.3 MPa) make Venus much different than Earth. The atmospheric pressure at the planet's surface is 92 times that of the Earth (a pressure equivalent to that at a depth of nearly 1 kilometer under Earth's oceans). At its closest, Venus is only 42 million kilometers (26 million miles) from Earth. Venus has the densest atmosphere of all the terrestrial planets in the Solar System, consisting mostly of carbon dioxide  and a small amount of nitrogen. The CO2-rich atmosphere, along with thick clouds of sulfur dioxide, generates the strongest greenhouse effect in the Solar System, creating surface temperatures of over 460 °C (860 °F). This makes Venus the hottest planet in the solar system.


Venus: Facts & Figures


Venus Fact Sheet


Venus is always brighter than any star outside our solar system. The greatest luminosity, apparent magnitude −4.9, occurs during crescent phase when it is near the Earth. Venus fades to about magnitude −3 when it is backlit by the Sun. The planet is bright enough to be seen in the middle of the day when the sky is very clear, and the planet can be easy to see when the Sun is low on the horizon. As an inferior planet, it always lies within about 47° of the Sun. 

The clouds of Venus are capable of producing lightning much like the clouds on Earth. The existence of lightning had been controversial since the first suspected bursts were detected by the Soviet Venera probes. In 2006–07 Venus Express clearly detected whistler mode waves, the signatures of lightning. Their intermittent appearance indicates a pattern associated with weather activity. The lightning rate is at least half of that on Earth.  In 2007 the Venus Express probe discovered that a huge double atmospheric vortex exists at the south pole of the planet.  Another discovery made by the Venus Express probe in 2011 is that an ozone layer exists high in the atmosphere of Venus.



Hubble's observations of Venus show that the atmosphere continues to recover from an intense bout of sulfuric "acid rain," triggered by the suspected eruption of a volcano in the late 1970's. This is similar to what happens on Earth when sulfur dioxide emissions from coal power plants are broken apart in the atmosphere to make acid rain. On Venus, this effect takes place on a planetary scale. About 80% of the Venusian surface is covered by smooth volcanic plains, consisting of 70% plains with wrinkle ridges and 10% smooth or lobate plains. Venus has several times as many volcanoes as Earth, and it possesses some 167 large volcanoes that are over 100 km across. The absence of evidence of lava flow accompanying any of the visible caldera remains an enigma.

The planet has few impact craters, demonstrating that the surface is relatively young, approximately 300–600 million years old. Earth's crust is in continuous motion, but it is thought that Venus cannot sustain such a process. Without plate tectonics to dissipate heat from its mantle, Venus instead undergoes a cyclical process in which mantle temperatures rise until they reach a critical level that weakens the crust. Then, over a period of about 100 million years, subduction occurs on an enormous scale, completely recycling the crust.





Discovered By

Known by the Ancients

Known by the Ancients

Date of Discovery

Unknown

Unknown

Average Orbit Distance

108,209,475 km

149,598,262 km

Perihelion (closest)

107,476,170 km

147,098,291 km

Aphelion (farthest)

108,942,780 km

152,098,233 km

Equatorial Radius

6,051.8 km

6,371.00 km

Equatorial Circumference

38,024.6 km

40,030.2 km

Volume

928,415,345,893 km3

1,083,206,916,846 km3

Mass

4,867,320,000,000,000,000,000,000 kg

5,972,190,000,000,000,000,000,000 kg

Density

5.243 g/cm3

5.513 g/cm3

Surface Area

460,234,317 km2

510,064,472 km2

Equatorial Surface Gravity

8.87 m/s2

9.80665 m/s2

Escape Velocity

37,296 km/h

40,284 km/h

Rotation Period (Length of Day)

-243.018 sidereal days (retrograde)

0.99726968 sidereal days

Orbit Period (Length of Year)

0.61519726 sidereal years

1.0000174 sidereal years

Mean Orbit Velocity

126,074 km/h

107,218 km/h

Orbit Eccentricity

0.00677672

0.01671123

Orbit Inclination to Ecliptic

3.39 degrees

0.00005 degrees

Equatorial Inclination to Orbit

177.3 degrees (retrograde rotation)

23.4393 degrees

Orbit Circumference

679,892,378 km

939,887,974 km

Minimum/Maximum Surface Temperature

462 °C

-88/58 (min/max) °C

Atmospheric Constituents

Carbon Dioxide, Nitrogen

Nitrogen, Oxygen

Compare All Eight Planets



Venus rotation

The Earth takes one day to rotate on its axis, and it takes one year to revolve around the Sun in orbit. But Venus takes 243 days to turn once on its axis, and it takes almost 225 days to travel once around the Sun in orbit. As you can see, a day on Venus is longer than its year. If you were standing on the surface of Venus you would see the Sun rise in the west and then take 117 days to travel across the sky and then set in the east.

Animation of the rotation of the Venus

And there’s another aspect of Venus that’s different from Earth; Venus rotates backwards. All the planets of the Solar System orbit in a counter-clockwise direction as viewed from above the Sun's north pole, but Venus rotates clockwise. This is called "retrograde" rotation. Astronomers think that Venus was impacted by another large planet early in its history, billions of years ago. The combined momentum between the two objects averaged out to the current rotational speed and direction. There are suggestions that Venus may have formed from the solar nebula with a different rotation period and obliquity, reaching to its current state because of chaotic spin changes caused by planetary perturbations and tidal effects on its dense atmosphere, a change that would have occurred over the course of billions of years.

When Venus lies between the Earth and the Sun, a position known as "inferior conjunction", it makes the closest approach to Earth of any planet, lying at an average distance of 41 million km during inferior conjunction.  The planet reaches inferior conjunction every 584 days, on average. Due to the decreasing eccentricity of Earth, the minimum distances will become greater. From the year 1 to 5383, there are 526 approaches less than 40 million km; then there are none for about 60,200 years. During periods of greater eccentricity Venus can come as close as 38.2 million km. 

Winds near the surface are only strong enough to move sand grains and dust particles, but the upper layers of the atmosphere move very fast. They circle the planet every four days, a pattern called super-rotation. Venus also has atmospheric circulation patterns between the equatorial and polar areas, similar to those on Earth.

Venus and Sun interaction

The diameter of Venus is 12,103 km, while the diameter of the Sun is 1.4 million km. In other words, the Sun is 115 times larger than Venus. You could fit about 1.5 million planets the size of Venus inside the Sun. The Sun has an enormous impact on Venus. The radiation from the Sun is trapped by the thick atmosphere of Venus, raising average temperatures across the planet to around 460 °C. In fact, this makes Venus the hottest planet in the Solar System.

Both the Sun and Venus formed at the same time, some of our scientists say, 4.6 billion years ago, with the rest of the Solar System. They formed out of the solar nebula, a cloud of gas and dust that collapsed down to become the Sun and planets. Because Venus orbits closer to the Sun than the Earth, we always see it close to the Sun in the sky. Venus is either trailing the Sun or leading it across the sky. The best times to see Venus are just before sunrise or just after sunset.



The Venusian magnetic field is much weaker than that of the Earth. This magnetic field is induced by an interaction between the ionosphere and the solar wind, rather than by an internal dynamo in the core like the one inside the Earth. Venus' small induced magnetosphere provides negligible protection to the atmosphere against cosmic radiation. This radiation may result in cloud-to-cloud lightning discharges. The weak magnetosphere around Venus means that the solar wind is interacting directly with the outer atmosphere of the planet. Here, ions of hydrogen and oxygen are being created by the dissociation of neutral molecules from ultraviolet radiation.



The solar wind than supplies energy that gives some of these ions sufficient velocity to escape the planet's gravity field. This erosion process results in a steady loss of low mass hydrogen, helium, and oxygen ions, while higher mass molecules such as carbon dioxide are more likely to be retained. Atmospheric erosion by the solar wind most likely led to the loss of most of the planet's water during the first billion years after it formed. The erosion has increased the ratio of higher mass deuterium to lower mass hydrogen in the upper atmosphere by a multiple of 150 times the ratio in the lower atmosphere.

Anyhow, with recent mysteries of giant storm on Saturn and missing spot on Jupiter, now we got new mystery related to Venus. Our planetary system is changing, there is no doubt about it. Is our planet next on the list of changing planetary environment? Well, we shall see...

Featured image: Global radar view of the surface from Magellan radar imaging (Credit:NASA/JPL)

Tags: venus

Comments

Fernando 7 years ago

here’s been a lot of information and disinformation about the the celestial body know as Nibiru, the destroyer, wormwood, planetX, or a number of other names that it goes by. Of course ancient carvings on rock walls and the like only goes to add more evidence that this celestial body did visit us in the past. I’m not going to talk about it’s history you can Google that if you want. I’m going to present what I think is proof positive that Nibiru is out there and is right on schedule to swing around the sun around the 21st of December 2012. I first want to present a picture that was taken in 2007 by someone using the South Pole telescope, who posted it on Youtube which was soon taken down. This is the picture that allegedly was taken. Nibiru with the coordinates : 5h 53m 27s-6 10′ 58. Now a very interesting thing happens if you plug these coordinates into Google sky. You will find when you hit search that you will come to a dark area. When you get there and slowly zoom out you will see that the area has been blocked out in the shape of a rectangle. This is the only place in Google sky where it was done. This begs the question why would they black out this picture? As with most cases there is always a work around and someone later found Nibiru on the world wide telescope using these coordinates: 06 08 55 22 27′ 24. The picture was exactly the same, a red object with the moons in the same place. After finding it on the world wide telescope people then used the same coordinate to find it on Google sky and although it had moved a bit they found it there at these coordinates: 06 08 55 22 47 14. You can check out these coordinates for yourself if you have Google Earth or The World Wide Telescope. Free downloads. From where it was first found in the above picture in Orion’s belt it has moved all the way over to Gemini. After finding Nibiru I did some calculations to try and determine it’s distance and size and here is how I went about it. The simple equation is : d=R/tan Ø In order to solve d, R ( the diameter of the object) must be known. There are ways to figure this out using triangulation where you get a measurement from one point on the earth and another from as far a distance from the first as possible. Then by using trigonometry you can calculate the size of object by knowing it’s distance. What I did in order to calculate the size of Nibiru was to take a measurement using the ruler on Google sky and measure the distance in km of Nibiru at a certain Ra and Dec and then at approximately the same Ra and Dec measure nearby Venus. Since the size of Venus is already known I simply took an approximation of the size of Nibiru. The size of Venus at about 8h and 25m was .25 km. While Nibiru was 1.01km, thus making Nibiru four times as large as Venus which is about the same size of the earth, making Nibiru about four times the size of earth or the size of Neptune. This diameter measures approx. 48,416 km or 4x the diameter of Venus which is 12,104 km. In order to solve for Ø I used the finder in world wide telescope to get the distance in arcsecs by traversing the diameter of the object then taking the difference in the readings. I converted this to degrees. Now that I have R to work with I can proceed to solve for d(distance). d=48,416 km/tanØ Ø=.02 degrees d=48,416/0.000349066 d=138,701,564.0 km=.927 au As far as calculating the speed of Nibiru I’ll save that for later if it’s possible. I heard that it was traveling at 35,000 mph if true that would be about right for a Dec 21 encounter. 138,701,564 km = 86185156.2 miles/35,000 mph= 102.6 days That means it would be here by Nov. 15 2012 again not sure of the speed but that is close enough. I haven’t been able to actually come up with an accurate idea of where Nibiru is in relation to the solar system and other planet only that is indeed close. If anyone cares to add to this post I’d appreciate some more information concerning the where about of Nibiru.

James D. Laughead 7 years ago

With the Green House gases increasing more and more on earth, one day, we might just become like Venus.

Tiffy (@James D. Laughead) 7 years ago

WE used to be like Venus we will be like mars next .. Our planetary system is a like how a planet evolves.. we 1st look like Mercury then Venus, then Earth then Mars after a few billion years we turn into Jupiter and on and on...

Sunflower Jacquie on Facebook 7 years ago

what about the Nibiru moon that was spotted in Antartic this month and Hawaii's telecam....could be the reason

Emreskopi 7 years ago

It says 6.5 minutes shortened but says also it slowed down. Doesn't shortening makes it faster? A mistyping? Please help me understand, if its all right.

Paul Felix Schott 7 years ago

QUESTION Venus rotation shortened for 6,5 minutes. What’s causing the planet to slow down? ANSWER Thy Lord GOD that art in Heaven. Read Matthew 24: 1-51 the whole chapter when you have done so go back and read Matthew 24:21and 22. then LUKE 21:11 in your Heart you will know then. GOD Bless You and Your Love ones Give thanks to our Lord Jesus Christ every day. The Lord's Little Helper Paul Felix Schott

jefferson jinks 7 years ago

When I vacationed on Venus, last WInter , it was much more temperate. It only got to 227 degrees F and the cool breezes at night cooled us to 184 degrees F. The article is talking about this years temperatures. Yikes.....now I know why I did not get a Vacation Venus in the Winter brochure this winter, Damn , the beaches on Venus are TO DIE FOR !!!!!!

Nikola Milovic 7 years ago

Today's science has two delusions related to kinematic-dynamic characteristics of the planets. 1)-planetary spin is a consequence of the accumulated energy in the perihelion. Should know that the kinetic energy of spin and radial motion are equal. . Wrong is Koenig's theorem and the existence of a translating movement of the conical motion. 2)-retrograde rotation is not a consequence of some ancient collision, but it is a mutual respect of three vectors that cause the retrogression of the planets. These vectors are: momentum, its own absolute angular velocity, spin and spin prečesione. Venus can be either flattened or elongated along the axis of rotation, but depending on the schedule above vectors may have retrograde rotation in both cases.

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