Kutkhiny Baty in Russia is a pumice rock formation.
Pumice is created when super-heated, highly pressurized rock is rapidly ejected from a volcano. Rapid cooling &rapid depressurization cause dissolved gas to come out of the lava, creating the foamy rock. Pumice's density can be as low as 0.7g/cm³.
#Oreum (오름) refers to the 360 small extinct volcanoes on #Jeju Island. They are commonly described as parasitic cones. They were lava outlets for the major volcano Hallasan that created Jeju between 2 million and 100 000 years ago.
@geraldkutney.bsky.social The Supreme Court’s sad decision to block the Obama administration’s Clean Power Plan before lower courts finished reviewing it.
(10/10) This issue is one of too many reminders of how regulators are always running late after we get unseen and/or ignored effects of a new technology. (Although in this case, it's related to having a huge rise in the use of old technology.) True progress does not proceed with horseblinders.
(9/10) Here is another fresh paper on space debris, again without a paywall. www.sciencedirect.com/science/arti...
(8/10) Using highly sensitive lasers, Wing and his team of international researchers observed a plume of lithium pollution, tracking it back to the uncontrolled re-entry of a discarded Space X Falcon 9 rocket upper stage. theconversation.com/spacex-rocke...
(7/10) Here is a paper on the topic from Geophysical Letters: agupubs.onlinelibrary.wiley.com/doi/10.1029/... There is no paywall
(6/10) Iodine is even more efficient than bromine at reacting with ClO, but luckily the heavier halogen is rarer in the statosphere. Learn more here: theconversation.com/defunct-sate...
(5/10) ...in the lower stratosphere. But Br avoids the reaction with O by reacting instead BrO with ClO:
First:
Br + O₃ -->BrO + O₂; then
BrO + ClO --> Br + O₂ + Cl
This O- independent step is fast and it generates a pair of ozone destroyers simultaneously-- the chlorine and bromine free radicals
(4/10) bromine can contribute a disproportionately large fraction of ozone loss due its higher catalytic efficiency. Why is that so? When Cl attacks ozone:
Cl + O₃ -->ClO + O₂
Cl + O --> Cl+ O₂, this 2nd reaction is the bottleneck-- the slow, rate-determining step because of O' s scarcity...
(3/10)..in the stratosphere. Al₂O₃ can also couple bromine and chlorine cycles.
HOBr + HCl --> BrCl + H₂O
BrCl + uv--> Br + Cl
This cross-reaction is a major amplifier of ozone depletion, especially above Antarctica, where we have an ozone hole. Even at 1% of the abundance of Cl....
(2/10) At 15-50 km in altitude, this is where the protective ozone(O₃) layer is. Al₂O₃ provides the surface for chemical reactions, converting otherwise inactive forms of chlorine like HCl, ClONO₂, & HOCl into sources of Cl radicals. These catalyze the breakdown of O₃. Al₂O₃ persists for years...
(1/10) Space Debris & #Ozone Destruction: when satellites & rocket bodies reenter the atmosphere, intense heat oxidizes aluminum components, forming fine Al₂O₃ particles. Number of such particles is on the rise with Space X's increasing launch rates. Most of these end up in the stratosphere.
A #paradox is a statement or idea that seems self-contradictory but may contain a deeper truth. Example, in #science, the more you discover, the more ignorant you feel.
#Cavitation damages everything from propellers to brains. It happens when pressure drops cause liquids to form vapor bubbles. When these eventually collapse, they create shock waves. Source: YouTube share.google/1MeWIYAKY6MF...
More tafoni.... bsky.app/profile/scie...
Key mechanism behind #tafoni formation is salt crystallization: seawater spray (or salty groundwater) seeps into tiny pores in the rock.
As water evaporates, salt crystals grow inside the pores.
They expand & exert pressure, slowly breaking apart the rock from within. Tafoni from Jeju's Sanbangsan:
Don't forget an atmosphere without excess greenhouse gases.
The drive to understand the natural world is a natural part of being human.
(7/7) Halley actually has multiple dust tails www.eso.org/public/image... from its rotating nucleus with multiple jets and from dust particles that separate by size. Unlike the ion tail which is bluish & straight, the dust tails are curved and yellowish from sand & organics reflecting light.
(6/7) (2) Dust tail: The escaping gas doesn’t leave quietly. It blasts outward in jets & acts like a spray, carrying along:
dust grains, sand-sized particles and tiny rocky debris. Photons from the Sun exert a tiny push. Over millions of km, the push is enough to sweep the dust away from the comet.
(5/7) Halley is only about 11 km in diameter and shaped like an avocado. It has two tails. (1) The ion tail comes from sublimated gases that have been ionized by the sun's UV rays. The gaseous ions then interact with the solar wind, the ions that stream from the Sun. How then do get the dust tail?
(4/7) Comets like Halley were probably not a significant source of H₂O for Earth, given that its ²H to ¹H ratio is unlike that of our oceans. But Mb isotope studies suggest that Theia, the colliding body that formed our moon, could have brought us lots of organics and water from the Oort cloud.
(3/7) Its period is about 75 years, which means that for most people, seeing it is a once in a lifetime opportunity. Its orbit is highly elliptical with an eccentricity of 0.967, with a closest approach of only 0.59 AU. But it's 35 AU at aphelion, roughly where Pluto is.
(2/7)From observations Edmond Halley made in 1682, he used Newton's law of universal gravitation to compute the periodicity of Halley's Comet in 1705. It was named after him upon its predicted return in 1758, which he never lived to see. It marked the first realization that some comets return.
(1/7)Halley's #Comet disappointed when it was last visible to the naked eye in 1986 because at perihelion ( closest approach to the sun) it was behind the sun. In 2061, that will not be the case. It will have a magnitude of 0 to -1, so it will be as bright as Saturn & visible at dusk and dawn.
The #tetrahedron is key to #organicChemistry & life. But it's also important along shorelines. Tetrapods are made of concrete, and use a tetrahedral shape to dissipate the force of incoming waves by allowing water to flow around rather than against them, and to reduce displacement by interlocking.
This is why you should carry a #compass on vacation. You never know when you'll stumble upon sone magnetite.
C/2025 R3 (PanSTARRS) is a hyperbolic Oort cloud comet. We don't know if it'll survive perihelion passage on 19 April 2026 when it passes 0.499 AU (75 million km) from the Sun. Around perihelion it may reach a naked eye visibility of about apparent magnitude +3. ( photo from D. Katevainis)
Galileo proved that Venus orbits the Sun, not the Earth. For one, he noticed that when #Venus was a crescent, it looked much larger than when it was full.