On This Day, But In 1974 The NASA Spacecraft Mariner 10 Made Its Closest Approach To Venus.

'Sail-Rover' could make Venus exploration possible.

NASA’s Innovative Advanced Concepts program is funding a study into the possible use of a sail powered rover to explore the 500°C surface temperatures of Venus.

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Venus as seen from the Mariner 10 probe taken in 1974

Wind hitting Venus’s mountains makes the planet rotate faster

Turbulent atmosphere speeds Venus’s days by a full 2 minutes

Venusian mountains impact its rotation

Night sky just after sunset on March 24, 2012 with crescent moon and backlight, Jupiter, Venus and the Pleiades.

by Ritzelmut

Ten interesting facts about Mars

The ancient Sumerians believed that Mars was Nergal, the god of war and plague. During Sumerian times, Nergal was a minor deity of little significance, but, during later times, his main cult center was the city of Nineveh. In Mesopotamian texts, Mars is referred to as the “star of judgement of the fate of the dead”. The existence of Mars as a wandering object in the night sky was recorded by the ancient Egyptian astronomers and, by 1534 BCE, they were familiar with the retrograde motion of the planet. By the period of the Neo-Babylonian Empire, the Babylonian astronomers were making regular records of the positions of the planets and systematic observations of their behavior. For Mars, they knew that the planet made 37 synodic periods, or 42 circuits of the zodiac, every 79 years. They invented arithmetic methods for making minor corrections to the predicted positions of the planets.

Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury.

The bright rust color Mars is known for is due to iron-rich minerals in its regolith — the loose dust and rock covering its surface. The soil of Earth is a kind of regolith, albeit one loaded with organic content. According to NASA, the iron minerals oxidize, or rust, causing the soil to look red.

The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System.

Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan.

There are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Future astrobiology missions are planned, including the Mars 2020 and ExoMars rovers. Liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is less than 1% of the Earth’s, except at the lowest elevations for short periods. The two polar ice caps appear to be made largely of water. The volume of water ice in the south polar ice cap, if melted, would be sufficient to cover the entire planetary surface to a depth of 11 meters (36 ft). In November 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior.

Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 kilometers (190 mi) across when Earth and Mars are closest because of Earth’s atmosphere.

Like Earth, Mars has differentiated into a dense metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ± 65 kilometers (1,115 ± 40 mi), consisting primarily of iron and nickel with about 16–17% sulfur. This iron(II) sulfide core is thought to be twice as rich in lighter elements as Earth’s. The core is surrounded by a silicate mantle that formed many of the tectonic and volcanic features on the planet, but it appears to be dormant. Besides silicon and oxygen, the most abundant elements in the Martian crust are iron, magnesium, aluminum, calcium, and potassium. The average thickness of the planet’s crust is about 50 km (31 mi), with a maximum thickness of 125 km (78 mi). Earth’s crust averages 40 km (25 mi).

Mars lost its magnetosphere 4 billion years ago, possibly because of numerous asteroid strikes, so the solar wind interacts directly with the Martian ionosphere, lowering the atmospheric density by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Expresshave detected ionised atmospheric particles trailing off into space behind Mars, and this atmospheric loss is being studied by the MAVEN orbiter. Compared to Earth, the atmosphere of Mars is quite rarefied.

Mars’s average distance from the Sun is roughly 230 million kilometres (143,000,000 mi), and its orbital period is 687 (Earth) days. The solar day (or sol) on Mars is only slightly longer than an Earth day: 24 hours, 39 minutes, and 35.244 seconds. A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours

Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of 5 km (3.1 mi) or greater have been found. The largest confirmed of these is the Hellas impact basin, a light albedo feature clearly visible from Earth. Due to the smaller mass of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, i.e., those that lie within the orbit of Jupiter. In spite of this, there are far fewer craters on Mars compared with the Moon, because the atmosphere of Mars provides protection against small meteors and surface modifying processes have erased some craters.

Martian craters can have a morphology that suggests the ground became wet after the meteor impacted.

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images: NASA/JPL-Caltech/Univ. of Arizona , ESA, Tunç Tezel

astronomy facts

The sky seemed to smile over much of planet Earth. Visible the world over was an unusual superposition of our Moon and the planets Venus and Jupiter. A crescent Moon over Los Angeles appears to be a smile when paired with the planetary conjunction of seemingly nearby Jupiter and Venus.

Clearest image ever taken of Venus. Photo by JAXA.

SpaceTime 20180309 Series 21 Episode 19 is now out

SpaceTime covers the latest news in astronomy & space sciences.

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Today’s stories…

The strange dense structure discovered below the South Atlantic Anomaly A strange dense structure has been discovered directly below the South Atlantic Anomaly and just above the Earth’s core mantle boundary. The object may provide important clues about the Earth’s magnetic field and when it’s next likely to reverse polarity.

New gravity mission to monitor climate change NASA’s next Earth Gravity mission is slated to launch aboard a SpaceX Falcon 9 rocket from the Vandenberg Air Force Base in California on April 14. The twin GRACE-FO spacecraft will continue the work of the original GRACE mission, monitoring how climate change caused by man’s use of fossil fuels was affecting the planet.

New exotic state of matter created Scientists have provided proof for a new state of matter comprising an electron orbiting an atomic nucleus at such a great distance – the space between the two can contain other bound atoms. The discovery raises new questions about the definition of an atom.

The Science Report The deadly legacy of asbestos is only now reaching its peak. Police to deploy drone killers at next month’s Commonwealth Games. Australians dying from alcohol-attributable diseases at the rate of one every 90 minutes. Taking selfies really does make your nose look bigger. A skeptic’s guide to water divining.

SpaceTime Background SpaceTime is Australia’s most respected astronomy and space science news program. The show reports on the latest stories and discoveries making news in astronomy, astrophysics, cosmology, planetary science, galactic and stellar evolution, physics, spaceflight, and general science. SpaceTime features interviews with leading Australian scientists about their latest research. The show is broadcast coast to coast across the United States by the National Science Foundation on Science360 Radio, and is available in Australia as a twice weekly podcast which averages around three million downloads annually. It’s hosted through Bitez.com on all major podcast platforms. SpaceTime is also available as inflight entertainment on Virgin Australia Airlines and on Tune in Radio. The SpaceTime program began life in 1995 as ‘StarStuff’ on ABC NewsRadio. Stuart Gary created the show while he was NewsRadio’s Science Editor and evening News anchor. Gary wrote, produced and hosted the program, consistently achieving almost 9 percent of the Australian national radio audience share - according to the Neilsen ratings survey figures for the five major Australian metro markets (Sydney, Melbourne, Brisbane, Adelaide, & Perth). The StarStuff podcast was hosted by ABC Science on line achieving over 1.3 million downloads annually. The program was axed in 2015 following ABC budget cuts. Gary resigned from the ABC, taking the show and audience with him and rebranding it as SpaceTime. The first SpaceTime episode was broadcast on February 8th 2016 and the show has been in production twice weekly ever since.

Bruce McCandless II (June 8, 1937 – December 21, 2017)

Rest In Peace