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November 2, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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November 1, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 31, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 30, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 29, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 28, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 27, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 26, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 25, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 24, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 23, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 22, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 21, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 20, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 19, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 18, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 17, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 16, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 15, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 14, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 13, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 12, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 11, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 10, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 9, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 8, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 7, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 6, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 5, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 4, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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October 3, 2026NASA Science

What’s causing this unusually long cloud on Mars? Known as the Arsia Mons Elongated Cloud (AMEC) and first recorded by NASA’s Viking Orbiter 2 in 1977, the strange cloud has been imaged in greater detail more recently by ESA’s robotic Mars Express spacecraft. The featured image is from 2018. The cloud forms only during spring and summer seasons and then only during morning hours. Made of water-ice, the most familiar process that causes cloud crystals to form around bits of dust would fail due to the thinness and lack of dust high in the Martian atmosphere. Leading speculation holds that dust is not involved. After the cloud forms near the volcano Arsia Mons, wind blows the cloud downstream — creating a tail that can extend over 1500 kilometers. Efforts to better understand AMECs will continue, an understanding that may bolster a more complete view of cloud formation on Earth.Tomorrow's picture: eyeing a cat

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