Sunday, February 19, 2023

3879 - VENUS - our sister planet?

 

-  3879  -   VENUS  -  our sister planet?   The “Mercury probe” provided new info about Venus.“BepiColombo” and “Solar Orbiter” are also helping us better understand Earth's sister planet.  The two probes en route to the sun, recently passed by Venus at nearly the same time, visiting Earth's sister planet within a day of each other in August 2021.

             


                  -----------------------  3879  -   VENUS  -  our sister planet?

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-    BepiColombo had a perfect view of the different regions within the magnetosheath and magnetosphere.   Earth's magnetic field is a key reason why life has been so successful here. Magnetic fields help deflect high-energy particles streaming from the sun, known as the solar wind, protecting the fragile atmosphere of the planet. Venus doesn't have a magnetic field created deep in its core like Earth does.

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-   However, Venus does have something known as an "induced" magnetic field, in which the solar wind interacts with charged particles in Venus' atmosphere to create a magnetosphere surrounding the planet.

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-     Solar Orbiter passed by Venus just outside this magnetosphere, observing the solar wind in its calm, undisturbed state. At the same time, BepiColombo zipped through the "stagnation region," the area where the solar wind and atmosphere are expected to interact at Venus.

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-    Together, the probes' observations provided experimental evidence that charged particles are, in fact, slowed down by this region, protecting Venus' atmosphere from erosion by the solar wind.

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-    This is also an important finding for planets beyond our solar system, since astronomers now know there is a way for exoplanets without an internal magnetic field to retain their atmospheres like Venus has and therefore possibly even harbor life.

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-    Venus is still the hottest and brightest planet in the solar system.   Venus' atmosphere traps heat from the sun as an extreme version of the greenhouse effect that warms Earth. The temperature on Venus are hot enough to melt lead.

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-   The scorching planet is named after the Roman goddess of love and beauty and is the only solar system planet named after a female.  In ancient Greek city-states, however, Venus was called Aphrodite.

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-------------------------------  VENUS FACTS:

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-----------------------  Length of day:        243 Earth days

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-----------------------   Length of year:      225 Earth days

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-----------------------  Distance from sun:      67 million miles

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            -----------------------  Number of moons:       0

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            -----------------------  Surface temperature:       900° F (480° C)

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            -----------------------  Diameter: 7,520 miles (12,100 km)

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            ---------------  Atmospheric composition: 96% carbon dioxide, 3% nitrogen.

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-    In ancient times, Venus was often thought to be two different stars, the evening star and the morning star, that is, the ones that first appeared at sunset and sunrise. In Christian Latin, they were respectively known as Vesper and Lucifer. (In Christian times, Lucifer, or "light-bringer," became known as the name of Satan before his fall.)

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-   Venus is highly visible from Earth due to its reflective clouds. In the sky, Venus appears as a brilliant white object that is one of the brightest natural things in the night sky. Its maximum magnitude, or apparent brightness, is close to -5.   By comparison, the moon is roughly -14, The lower an object's magnitude, the brighter it appears to the eye.

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-    Up close the color of Venus is "rusty", but not the kind of deep red rust one would find on the planet Mars. Rather, pictures NASA and others have sent back from Venus suggest a world with tinges of red, brown and yellow. That color comes from the number of volcanic rocks dotting the surface, as Venus is a highly active world.

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-    The "real" color of Venus, however, is impossible to see from orbit due to the sulfuric acid clouds surrounding the planet. Pictures of Venus are thus only visible if an orbiting satellite has the ability to peer through the thick clouds.

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-    For a human explorer to see the surface, they would need to descend and to survive the oven-like temperatures and high pressures present down there. That harsh environment likely means that for now, we'll be using robotic explorers to look at Venus for us.

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-    The orbit of Venus lies along the ecliptic, which is the same pathway that the other planets, the sun and the moon also take in our solar system. That's no coincidence, as the ecliptic represents the "plane" or the orientation of our solar system

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-    Venus and Earth are often called twins because they are similar in size, mass, density, composition and gravity. Venus is only a little bit smaller than our home planet, with a mass of about 80% of Earth's.

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-   Venus is not a gas planet, but a rocky planet. The interior of Venus is made of a metallic iron core that's roughly 2,400 miles wide. Venus' molten rocky mantle is roughly 1,200 miles  thick. Venus' crust is mostly basalt and is estimated to be 6 to 12 miles thick.

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-    Why Venus is the hottest planet in the solar system is rather complicated. Although Venus is not the planet closest to the sun, its dense atmosphere traps heat in a runaway version of the greenhouse effect that we see firsthand on Earth with global warming. 

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-   Temperatures on Venus reach 880 degrees Fahrenheit, which is more than hot enough to melt lead. Spacecraft have survived only a few hours after landing on the planet before being destroyed.

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-    With scorching temperatures, Venus also has a hellish atmosphere, that consists mainly of carbon dioxide with clouds of sulfuric acid and only trace amounts of water. The atmosphere of Venus is heavier than that of any other planet, leading to a surface pressure that's over 90 times that of Earth,  similar to the pressure that exists 3,300 feet deep in the ocean. 

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-   Venus' surface is extremely dry. During the planet's evolution, ultraviolet rays from the sun evaporated water quickly, keeping Venus in a prolonged molten state. There is no liquid water on its surface today because the scorching heat created by its ozone-filled atmosphere would cause water to immediately boil away.

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-    Roughly two-thirds of the Venusian surface is covered by flat, smooth plains that are marred by thousands of volcanoes, some of which are still active today, ranging from about 0.5 to 150 miles wide, with lava flows carving long, winding canals that are up to more than 3,000 miles  in length.

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-    Six mountainous regions make up about one-third of the Venusian surface. One mountain range, called Maxwell, is about 540 miles long and reaches up to some 7 miles  high, making it the highest feature on the planet.

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-    Venus also possesses several surface features that are unlike anything on Earth.   Venus has coronae, or crowns, ring-like structures that range from roughly 95 to 1,300 miles wide. Scientists believe these formed when hot material beneath the planet's crust rose, warping the planet's surface. Venus also has 'tesserae”, or tiles raised areas in which many ridges and valleys have formed in different directions.

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-    Venus has no known moons, which makes it nearly unique in our solar system. The only other designated planet without moons is Mercury, which is quite close to the sun.

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-    Venus takes 243 Earth days to rotate on its axis, which is by far the slowest of any of the major planets. In fact, its day is longer than its year, and that may be due to the thick atmosphere of Venus serving as a big brake on the planet's rotation. And, because of this sluggish spin, its metal core cannot generate a magnetic field similar to Earth's. The magnetic field of Venus is 0.000015 times that of Earth's magnetic field.

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------------------   Average distance from the sun: 67 million miles.

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------------------    Perihelion (closest approach to the sun): 66,785,000 miles .

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----------------    Aphelion (farthest distance from the sun): 67,692,000 miles . 

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-    If viewed from above, Venus rotates on its axis in a direction that's the opposite of most planets'. That means on Venus, the sun would appear to rise in the west and set in the east. On Earth, the sun appears to rise in the east and set in the west.

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-    The Venusian year, the time it takes to orbit the sun, is about 225 Earth days long. Normally, that would mean that days on Venus would be longer than years. However, because of Venus' curious retrograde rotation, the time from one sunrise to the next is only about 117 Earth days long. The last time we saw Venus transit in front of the sun was in 2012, and the next time will be in 2117.

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-    The very top layer of Venus' clouds zips around the planet every four Earth days, propelled by hurricane-force winds traveling roughly 224 mph. This superrotation of the planet's atmosphere, some 60 times faster than Venus itself rotates, might be one of Venus' biggest mysteries.

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-    The clouds also carry signs of meteorological events known as gravity waves, caused when winds blow over geological features, causing rises and falls in the layers of air. The winds at the planet's surface are much slower, estimated to be just a few miles per hour.

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-     Unusual stripes in the upper clouds of Venus are dubbed "blue absorbers" or "ultraviolet absorbers" because they strongly absorb light in the blue and ultraviolet wavelengths. These are soaking up a huge amount of energy, nearly half of the total solar energy the planet absorbs.   

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-    The Venus Express spacecraft, a European Space Agency mission that operated between 2005 and 2014, found evidence of lightning on the planet, which formed within clouds of sulfuric acid, unlike Earth's lightning, which forms in clouds of water. Venus' lightning is unique in the solar system. It is of particular interest to scientists because it's possible that electrical discharges from lightning could help form the molecules needed to jumpstart life, which is what some scientists believe happened on Earth.

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-    The United States, Soviet Union, European Space Agency and Japan Aerospace Exploration Agency have deployed many spacecraft to Venus, more than 20 so far. NASA's Mariner 2 came within 21,600 miles of Venus in 1962, making it the first planet to be observed by a passing spacecraft.

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-     The Soviet Union's Venera 7 was the first spacecraft to land on another planet, having landed on Venus in December 1970. Venera 9 returned the first photographs of the Venusian surface. The first Venusian orbiter, NASA's Magellan, generated maps of 98% of the planet's surface, showing features as small as 330 feet across.

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-    The European Space Agency's Venus Express spent eight years in orbit around Venus with a large variety of instruments and confirmed the presence of lightning there. In August 2014, as the satellite began wrapping up its mission, controllers engaged in a month-long maneuver that plunged the spacecraft into the outer layers of the planet's atmosphere.

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-    Venus Express survived the daring journey, then moved into a higher orbit, where it spent several months. By December 2014, the spacecraft ran out of propellant and eventually burned up in Venus' atmosphere.

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-    Japan's Akatsuki mission launched to Venus in 2010, but the spacecraft's main engine died during a pivotal orbit-insertion burn, sending the craft hurtling into space. Using smaller thrusters, the Japanese team successfully performed a burn to correct the spacecraft's course.

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-     A subsequent burn in November 2015 put Akatsuki into orbit around the planet. In 2017, Akatsuki spotted another huge "gravity wave" in Venus' atmosphere. The spacecraft still orbits Venus to this day, 2023, studying the planet's weather patterns and searching for active volcanoes.

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-    In 2021, NASA announced two new missions to Venus that will launch by 2030.  The agency announced on June 2, 2021, that they will be sending missions DAVINCI+ and VERITAS, chosen from a shortlist of four spacecraft, for the next round of Discovery missions to Venus.

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-   DAVINCI (Deep Atmosphere Venus Investigation of Noble Gases, Chemistry and Imaging) will dive through the planet's atmosphere, studying how it changes over time.

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-    VERITAS (Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy) will map the planet's surface from its orbit using radar.

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-    While destinations in our solar system like the moons Enceladus or Titan or even planet Mars are currently the go-to spots to search for signs of extraterrestrial life.    But a breakthrough scientific discovery in 2020 suddenly had scientists discussing whether or not it was possible that life could somehow exist in the present-day hellish atmospheres of Venus.

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-   In 2020, scientists revealed the discovery of a strange chemical in the planet's clouds that some think could be a sign of life: phosphine. Phosphine is a chemical compound that has been seen on Earth as well as on Jupiter and Saturn. Scientists think that, on Venus, it could appear as it does on Earth, for very short amounts of time in the planet's atmosphere.

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-    But what does this phosphine discovery have to do with the search for life?   While phosphine exists in strange ways such as rat poison, it has also been spotted alongside groups of certain microorganisms and some scientists think that, on Earth, the compound is produced by microbes as they decay chemically.

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-    This has caused some to suspect that, if microbes could create phosphine, then perhaps microbes might be responsible for the phosphine in Venus' atmosphere. Since the discovery, there have been follow-up analyses that have made some doubt whether or not the compound is created by microbes, but scientists are continuing to investigate, especially with new missions planned for the planet.

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February 16, 2023                                              3879                                                                                                                          

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