APOD: Comet ZTF over Yosemite Falls (2023 Feb 21)

[APOD Robot]

Comet ZTF over Yosemite Falls

Explanation: They are both falling. The water in Yosemite Falls, California, USA, is falling toward the Earth. Comet ZTF is falling toward the Sun. This double cosmic cascade was captured late last month as fading Comet C/2022 E3 (ZTF) had just passed its closest to planet Earth. The orange star just over the falls is Kochab. With the exception of a brief encounter with a black bear, the featured image was a well-planned composite of a moonlit-foreground and long-duration background exposures - all designed to reconstruct a deep version of an actual single sight. Although Comet ZTF is now fading as it glides back to the outer Solar System, its path is determined by gravity and so it can be considered to still be falling toward the Sun -- but backwards.

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[Guest]

That's actually Bridalveil Falls

[Chris Peterson]

Comet ZTF over Yosemite Falls

Explanation: They are both falling. The water in Yosemite Falls, California, USA, is falling toward the Earth. Comet ZTF is falling toward the Sun. This double cosmic cascade was captured late last month as fading Comet C/2022 E3 (ZTF) had just passed its closest to planet Earth. The orange star just over the falls is Kochab. With the exception of a brief encounter with a black bear, the featured image was a well-planned composite of a moonlit-foreground and long-duration background exposures - all designed to reconstruct a deep version of an actual single sight. Although Comet ZTF is now fading as it glides back to the outer Solar System, its path is determined by gravity and so it can be considered to still be falling toward the Sun -- but backwards.

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I think it's a bit marginal to say that a body in an open (hyperbolic) orbit that is moving faster than the Solar System escape velocity and will never return is really falling toward the Sun... in either direction.

[Chris Peterson]

That's actually Bridalveil Falls

No, it's Upper Yosemite Fall.

[Cousin Ricky]

The orange star just over the falls is Kochab. With the exception of a brief encounter with a black bear, ...

So, two bears in this description!

[johnnydeep]

Comet ZTF over Yosemite Falls

Explanation: They are both falling. The water in Yosemite Falls, California, USA, is falling toward the Earth. Comet ZTF is falling toward the Sun. This double cosmic cascade was captured late last month as fading Comet C/2022 E3 (ZTF) had just passed its closest to planet Earth. The orange star just over the falls is Kochab. With the exception of a brief encounter with a black bear, the featured image was a well-planned composite of a moonlit-foreground and long-duration background exposures - all designed to reconstruct a deep version of an actual single sight. Although Comet ZTF is now fading as it glides back to the outer Solar System, its path is determined by gravity and so it can be considered to still be falling toward the Sun -- but backwards.

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I think it's a bit marginal to say that a body in an open (hyperbolic) orbit that is moving faster than the Solar System escape velocity and will never return is really falling toward the Sun... in either direction.

Yeah. Plus, though "intuitively", a body in a closed elliptical orbit around the Sun is only falling toward it prior to perihelion, such an object is in reality falling toward the sun at all times! And even a rock thrown upward from the Earth's surface is falling even when it is rising!

So, does "falling" just mean the direction that gravity is acting regardless of the direction of motion of the object?

[orin stepanek]

Beautiful!