Fresh Tiger Stripes on Saturns Enceladus

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2020 April 27

Fresh Tiger Stripes on Saturn’s Enceladus
Image Credit: NASA, ESA, JPL, SSI, Cassini Imaging Team Explanation: How will humanity first learn of extraterrestrial life? One possibility is to find it under the icy surface of Saturn’s moon Enceladus. A reason to think that life may exist there are long features — dubbed tiger stripes — that are known to be spewing ice from the moon’s icy interior into space. These surface cracks create clouds of fine ice particles over the moon’s South Pole and create Saturn‘s mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft that orbited Saturn from 2004 to 2017. Pictured here, a high resolution image of Enceladus is shown from a close flyby. The unusual surface tiger stripes are shown in false-color blue. Why Enceladus is active remains a mystery, as the neighboring moon Mimas, approximately the same size, appears quite dead. A recent analysis of ejected ice grains has yielded evidence that complex organic molecules exist inside Enceladus. These large carbon-rich molecules bolster — but do not prove — that oceans under Enceladus’ surface could contain life. Another Solar System moon that might contain underground life is Europa.

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May 19, 2020

LDN 1471: A Windblown Star Cavity

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2020 May 6

LDN 1471: A Windblown Star Cavity
Image Credit: Hubble, NASA, ESA; Processing & License: Judy Schmidt Explanation: What is the cause of this unusual parabolic structure? This illuminated cavity, known as LDN 1471, was created by a newly forming star, seen as the bright source at the peak of the parabola. This protostar is experiencing a stellar outflow which is then interacting with the surrounding material in the Perseus Molecular Cloud, causing it to brighten. We see only one side of the cavity — the other side is hidden by dark dust. The parabolic shape is caused by the widening of the stellar-wind blown cavity over time. Two additional structures can also be seen either side of the protostar, these are known as Herbig-Haro objects, again caused by the interaction of the outflow with the surrounding material. What causes the striations on the cavity walls, though, remains unknown. The featured image was taken by NASA and ESA’s Hubble Space Telescope after an original detection by the Spitzer Space Telescope.