Corey S Powell
Corey S Powell  路  5 months ago

Content Warning

For the purists, here's a video of all lunar phases in 2025 with no labeling. It takes about 5 minutes to watch the full thing -- and what a sweet, meditative 5 minutes it is.

(Full video at link.)

https://svs.gsfc.nasa.gov/5415 #science #nature #sky #earth #moon

The Moon always keeps the same face to us, but not exactly the same face. Because of the tilt and shape of its orbit, we see the Moon from slightly different angles over the course of a month. When a month is compressed into 24 seconds, as it is in this animation, our changing view of the Moon makes it look like it's wobbling. This wobble is called libration. The word comes from the Latin for "balance scale" (as does the name of the zodiac constellation Libra) and refers to the way such a scale tips up and down on alternating sides. The sub-Earth point gives the amount of libration in longitude and latitude. The sub-Earth point is also the apparent center of the Moon's disk and the location on the Moon where the Earth is directly overhead. The Moon is subject to other motions as well. It appears to roll back and forth around the sub-Earth point. The roll angle is given by the position angle of the axis, which is the angle of the Moon's north pole relative to celestial north. The Moon also approaches and recedes from us, appearing to grow and shrink. The two extremes, called perigee (near) and apogee (far), differ by as much as 14%.
Corey S Powell
Corey S Powell  路  5 months ago

Content Warning

NASA's visualization team created a beautiful preview of every phase of the Moon in 2025, hour by hour.

The best part: Watching how the Moon's appearance changes due to its inclination, oval orbit, and libration (wobble).

https://svs.gsfc.nasa.gov/5415 #science #nature #nasa #astronomy #space

The phase and libration of the Moon for 2025, at hourly intervals. Includes supplemental graphics that display the Moon's orbit, subsolar and sub-Earth points, and the Moon's distance from Earth at true scale. Craters near the terminator are labeled, as are Apollo landing sites, maria, and other albedo features in sunlight.
Corey S Powell
Corey S Powell  路  5 months ago

Content Warning

Two unusual things happened on Earth around 460 million years ago: a bunch of asteroid impacts near the equator & an intense global cold spell.

Possibly both were the result of an asteroid that broke up & gave our planet a pretty but deadly set of rings.

https://eos.org/articles/a-close-asteroid-encounter-may-have-once-given-earth-a-ring #space #science #nature

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