Happy Thought for 23 June 2023

Have a Happy Thought: 

 

The new James Webb Space Telescope (JWST) is opening up the origins of the universe and very distant galaxies, stars and exoplanets to our understanding.

 You’d think we’re only looking that far because we’ve figured out how everything works closer to us, right?

 Wrong! Science is great because there’s always something new to explore and figure out.

Here are just a few of the mysteries that remain for us to solve, or maybe just a few things you didn’t know, right here in our own solar system:

 

Q: What is our sun’s surface actually made of?

A: We’re… not 100% sure, actually! We know mostly, by analysing the light that comes from the sun. You see, every time light passes through an object, including a bunch of gas, it changes the spectrum that we see – that object, or gas, absorbs some of the energy of light at specific wavelengths (or sometimes absorbs-and-re-emits-at-slightly-different-wavelengths). So astronomers can tell what gasses a star is made of, or in the atmosphere of a planet, by looking at the spectrum – by passing the light through a prism (yes, like the album cover for Pink Floyd’s The Dark Side of the Moon).

Anyway… so we can look at the sun’s spectrum, and use it to figure out what gasses are present.

The thing is though… some of these lines, we can’t figure out what they belong to, especially when we analyse in 4-D. And that’s just cool.

A rainbow of the Sun's colors is shown from deep red on the upper left

to deep blue on the lower right. Some horizontal lines have gaps

that appear dark where some colors are missing. 

 

Image Credit: Nigel Sharp (NSF), FTS, NSO, KPNO, AURA, NSF, https://apod.nasa.gov/apod/ap230611.html

 

Q: When can we see the dark side of the moon?

Image: Pink Floyd album cover, The Dark Side of the Moon

 

A: There is no “dark side” of the moon. Our moon is “tidally locked” to the Earth, meaning that the same face, or side, of the moon is always facing the Earth (with a little bit of wobble). This also means that as the Earth orbits the sun, and the moon orbits the Earth, all* sides of the moon are in direct sunlight, at some point of the month.

         * some parts at the poles only get sun at an angle, so deep crevasses can get little to no sunlight.

 

 

Q: So if I can’t see the “far side” of the moon from Earth, can I at least see the other side of planets?

A: Yes and no. Ok, yes. Due to orbits, and planet rotations, and really good telescopes, and sometimes robots, we can get a good look all the way around all of the other planets. Except Venus, kind of. See, Venus and Earth have this weird thing where every time we get the closest to each other in our orbits, the same side of Venus is facing the Earth. So our “closest look” is always the same. Weird, huh? The next time this is happening is August 18^th 2023 so… still time to buy a backyard telescope?

Sketch drawing showing the orbits of Venus and Earth around the sun, and at closest approach showing a fixed point on Venus facing the Earth.

Image still from the video linked above, Interplanetary on YouTube

 

Q: The Earth is huge, we can’t really change its orbit, even with a really long lever, right?

A: Wellll….. give us enough wells, and apparently we can! Scientists just this week announced that the Earth’s rotational pole has shifted due to all of the shifting of groundwater we’ve been doing. The rotational pole changes due to a lot of things, like glaciers and continents moving around. But apparently humans have moved so much fresh water that we’re contributing to over 4cm of movement per year!

(a) Individual contributors to the PM excitation trend. (b) Sum of PM excitation trend contributors with (solid blue) and without (dashed blue) groundwater depletion. Red arrow is the observed PM excitation, and aligns almost exactly with the solid blue arrow

Image: Drift of Earth's Pole Confirms Groundwater Depletion as a Significant Contributor to Global Sea Level Rise 1993–2010. Ki-Weon Seo, et al., First published in Geophysical Research Letters, Volume50, Issue12, 28 June 2023: 15 June 2023 https://doi.org/10.1029/2023GL103509, (CC BY-NC-ND 4.0)