Latest news with #mesosphere
Yahoo
14 hours ago
- Science
- Yahoo
The intriguing phenomena we can see in the skies this week
The summer evenings offer us the opportunity to sight some rather intriguing and beguiling phenomena. Noctilucent clouds, (NLCs), make for an interesting spectacle after sunset, observable with the naked eye and quite eerie in appearance. Around two hours after the Sun has set and looking above the northwest horizon, watch for wispy threads of cloud with a distinct blue and silver tinge to them. Taken from the Latin for 'night-shining', NLCs are formed by sunlight reflecting off high-altitude ice crystals that are positioned right on the edge of space. The time period after sunset is crucial if we are to catch NLCs, as around 90 minutes to two hours after the Sun has dipped below the horizon is when the necessary angle occurs for sunlight to catch the crystals and illuminate that part of the sky with this enchanting effect. The beautiful and captivating sight sees the highest clouds in our atmosphere, about 50 miles above the Earth's surface, seem to glow and shimmer with this mesmerizing blue or silvery guise. In the summertime the mesosphere, (the third layer of the Earth's atmosphere where meteorites burn up), becomes cold enough to allow ice to form on suspended dust particles that are floating around in the clouds. These particles may originate from meteorites falling from space, but equally so from other sources, possible volcanic, with the recent Mount Etna eruption billowing tons of debris into the atmosphere. In fact, the first NLCs observations were recorded in 1885, two years after the eruption of Krakatoa, which may or may not have something to do with their appearance. Eruptions aside, rockets that have blasted off from Earth leave particle emissions from their exhaust systems, all contributing to the array of debris circulating in our atmosphere. NLC's have been given a different name when seen from space looking back on Earth; polar mesospheric clouds, or (PMCs). However, the Earth is not the only place NLC's have been witnessed. Launched in June 2003, Mars Express was not only the first European mission to Mars, but the first planetary mission operated entirely by Europe. There were reports of NLC's made three years into the Mars Express mission in 2006, with NASA's Curiosity Mars rover confirming the presence of NLC's in 2019. Readers may well recall all the media hype over Asteroid 2024 YR4, which earlier this year was once considered the highest impact risk to Earth ever recorded. Earlier this week, NASA announced that previously collected data on the asteroid that has been reanalysed now reveals that the 174 to 220 feet-long chunk of rock is more likely to hit the Moon in 2032. During the week ahead, watch for Mars in the evening sky as it moves its way slowly night by night, left to right, above the bright star Regulus in the constellation of Leo, the Lion, situated above the western horizon. The International Space Station continues its early summer break and cannot be seen across our region at present. Send your astrophotography pictures to: thenightsky@
Forbes
23-05-2025
- Science
- Forbes
When To See Weird ‘Space Clouds' Glow After Sunset — And What They Are
Noctilucent clouds are reflected in a puddle in Sieversdorf, Germany, 5 July 2016. (Photo by Patrick ... More Pleul/picture alliance via Getty Images) If you're in the northern hemisphere and it's been a clear day, look at the northeastern night sky before bed. You may see something astonishingly beautiful — noctilucent ("night shining") clouds. These high-altitude clouds, formed in the coldest place in Earth's atmosphere at the edge of space, result from dust left by "shooting stars." Here's everything you need to know about the beginning of the noctilucent cloud season — and when and where to see them. Noctilucent clouds are Earth's highest clouds. They form between Earth and space, about 47–53 miles (76 to 85 kilometers) above the ground in the mesosphere. Noctilucent clouds can only be seen at twilight, shining after sunset, but they are never guaranteed. Visible as vast, wispy electric blue structures, they glow surprisingly brightly as blueish or silvery streaks in the twilight sky. They do so because, during the observation season, the sun is never far beneath the horizon, so it can illuminate the clouds for some time after it appears to have set, as seen from the Earth's surface. You don't need any special equipment to see noctilucent clouds. A superb and extensive 'grand display' of noctilucent clouds at dawn on July 16, 2022. (Photo by: ... More Alan Dyer/VW Pics/Universal Images Group via Getty Images) Noctilucent clouds are only seen in very limited times of day and times of year, depending on your location. The farther from the equator you are, the more likely you are to see them. They're typically seen from late May to August in the Northern Hemisphere and from November to February in the Southern Hemisphere. The timing means they effectively replace the possibility of aurora, but are sometimes confused with them. Noctilucent clouds form in the mesosphere, a layer of Earth's atmosphere about 22 miles (35 kilometers) thick. According to NASA, summer in the Northern and Southern Hemisphere is when the mesosphere is most humid, with water vapor rising from lower altitudes. Water vapor is one of the three essential ingredients for noctilucent clouds. Noctilucent clouds are thin, wispy clouds hovering at the edge of space. Noctilucent clouds are seeded by microscopic debris from disintegrating meteors and micro-meteors — "shooting stars!" When you see a shooting star streak across the sky, it's doing so in the mesosphere, where the friction of it hitting gases causes energy to be released as photons. As it disintegrates, it leaves a dust of sodium and iron atoms that settle upon tiny ice crystals that form in the -120°C (-184°F) temperatures. That also makes noctilucent clouds Earth's coldest clouds. Mix water vapor with meteoric dust and very cold temperatures, and the result can be noctilucent clouds. The sodium and iron atoms in the mesosphere are highly reflective. Enormous telescopes fire lasers at this part of the Earth's atmosphere to align their optics and correct for any turbulence. It also means that the metal-coated ice grains in noctilucent clouds reflect radar and, in theory, a lot of light. However, what you see when you look at noctilucent clouds is not the collective brightness of all the metal-coated ice grains but ripples within them reflecting as one, according to researchers at Caltech. An 1886 sketch by William Ascroft, documenting the meteorological effects of the eruption of ... More Krakatoa. (Photo) Noctilucent clouds are not an ancient sky sight. They were first observed in 1885, across the world, in the wake of the eruption of Krakatoa in Indonesia in 1883 — one of the most significant volcanic events ever recorded — which sent up a massive plume of ash into Earth's atmosphere. During the 20th century, they were seen more regularly between 40 and 50 degrees north latitude. NASA's Aeronomy of Ice in the Mesosphere (AIM) mission has been studying them since 2007 to determine if the mesosphere is changing and how that's linked to Earth's climate and/or the solar cycle. Wishing you clear skies and wide eyes.
