Aug 25, 2020 06:21 AM
(This post was last modified: Aug 25, 2020 06:45 AM by C C.)
Asteroid which ruffled Earth's gravity discovered by Indian students
https://akipress.com/news:647381:Asteroi..._students/
Earth appears to be travelling through the debris of ancient supernovae
https://www.sciencealert.com/earth-might...supernovae
INTRO: Radioactive dust deep beneath the ocean waves suggest that Earth is moving through a massive cloud left behind by an exploded star. Continuously, for the last 33,000 years, space has been seeding Earth with a rare isotope of iron forged in supernovae. It's not the first time that the isotope, known as iron-60, has dusted our planet. But it does contribute to a growing body of evidence that such dusting is ongoing - that we are still moving through an interstellar cloud of dust that could have originated from a supernova millions of years ago.
Iron-60 has been the focus of several studies over the years. It has a half-life of 2.6 million years, which means it completely decays after 15 million years - so any samples found here on Earth must have been deposited from elsewhere, since there's no way any iron-60 could have survived from the formation of the planet 4.6 billion years ago.
And deposits have been found. Nuclear physicist Anton Wallner of the Australian National University previously dated seabed deposits back to 2.6 million and 6 million years ago, suggesting that debris from supernovae had rained down on our planet at these times. But there's more recent evidence of this stardust - much more recent. It's been found in the Antarctic snow; according to the evidence, it had to have fallen in the last 20 years... (MORE - details)
Did Jupiter push Venus into a runaway greenhouse?
https://www.universetoday.com/147535/did...reenhouse/
EXCERPT: Numerous planetary scientists have focused on Venus’ formation and atmospheric development in the recent past. Now a new paper posits that Venus might have had liquid water on its surface as recently as one billion years ago. And a contributor to the disappearance of that water might be an unlikely culprit: Jupiter. There are various threads of evidence that Jupiter actually migrated to its current orbit from the inner solar system. ... What Dr Stephen Kane, a planetary scientist at UC Riverside and his co-authors were interested in was what effect that migration might have had on Venus.
Therefore, they simulated hundreds of thousands of different migration paths of Jupiter during the formation of the early solar system. There were plenty of simulation scenarios where Venus or one of the other terrestrial planets were flung out of the solar system, and those runs were discarded. However, there were also numerous scenarios where the orbit of Venus was severely affected. One measure of an orbit is called eccentricity, which is essentially how elliptical an orbit it. Some of the Jupiter migration models caused Venus to have an eccentricity 44 times what it currently does.
That is important because Venus currently has an extremely circular orbit, with low eccentricity. If the models of Jupiter’s migration through the early solar system caused Venus to have a high eccentricity, where did that eccentricity go? [...] Liquid water can dampen orbital eccentricities over long periods of times ... highly orbital eccentricities have another effect on liquid water. They cause it to disappear. This is a two-step process... (MORE - details)
Were the Scorching Conditions on Venus Once Earth-Like?
https://www.youtube-nocookie.com/embed/95fLlHaHmwk
https://akipress.com/news:647381:Asteroi..._students/
Earth appears to be travelling through the debris of ancient supernovae
https://www.sciencealert.com/earth-might...supernovae
INTRO: Radioactive dust deep beneath the ocean waves suggest that Earth is moving through a massive cloud left behind by an exploded star. Continuously, for the last 33,000 years, space has been seeding Earth with a rare isotope of iron forged in supernovae. It's not the first time that the isotope, known as iron-60, has dusted our planet. But it does contribute to a growing body of evidence that such dusting is ongoing - that we are still moving through an interstellar cloud of dust that could have originated from a supernova millions of years ago.
Iron-60 has been the focus of several studies over the years. It has a half-life of 2.6 million years, which means it completely decays after 15 million years - so any samples found here on Earth must have been deposited from elsewhere, since there's no way any iron-60 could have survived from the formation of the planet 4.6 billion years ago.
And deposits have been found. Nuclear physicist Anton Wallner of the Australian National University previously dated seabed deposits back to 2.6 million and 6 million years ago, suggesting that debris from supernovae had rained down on our planet at these times. But there's more recent evidence of this stardust - much more recent. It's been found in the Antarctic snow; according to the evidence, it had to have fallen in the last 20 years... (MORE - details)
Did Jupiter push Venus into a runaway greenhouse?
https://www.universetoday.com/147535/did...reenhouse/
EXCERPT: Numerous planetary scientists have focused on Venus’ formation and atmospheric development in the recent past. Now a new paper posits that Venus might have had liquid water on its surface as recently as one billion years ago. And a contributor to the disappearance of that water might be an unlikely culprit: Jupiter. There are various threads of evidence that Jupiter actually migrated to its current orbit from the inner solar system. ... What Dr Stephen Kane, a planetary scientist at UC Riverside and his co-authors were interested in was what effect that migration might have had on Venus.
Therefore, they simulated hundreds of thousands of different migration paths of Jupiter during the formation of the early solar system. There were plenty of simulation scenarios where Venus or one of the other terrestrial planets were flung out of the solar system, and those runs were discarded. However, there were also numerous scenarios where the orbit of Venus was severely affected. One measure of an orbit is called eccentricity, which is essentially how elliptical an orbit it. Some of the Jupiter migration models caused Venus to have an eccentricity 44 times what it currently does.
That is important because Venus currently has an extremely circular orbit, with low eccentricity. If the models of Jupiter’s migration through the early solar system caused Venus to have a high eccentricity, where did that eccentricity go? [...] Liquid water can dampen orbital eccentricities over long periods of times ... highly orbital eccentricities have another effect on liquid water. They cause it to disappear. This is a two-step process... (MORE - details)
Were the Scorching Conditions on Venus Once Earth-Like?