darrellbear

darrellbear t1_jd15rxf wrote

Before And After Science, also by Brian Eno, rocks. It's not instrumental, though. Taking Tiger Mountain is good too. Music For Airports is instrumental.

Explosions In The Sky has some great instrumental albums, The Earth Is Not A Cold Dead Place is a favorite.

Jean Michel Jarre's Equinoxe and Oxygene albums are great instrumental works as well. Equinoxe is an all time favorite.

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darrellbear t1_jcwbwi0 wrote

Reply to comment by ledfrisby in Moon and Mars by theillini19

Mars is about twice the diameter of the moon, ~4,000 miles vs ~2,000 miles. It appeared about 1/100th the size at the time of the occultation, meaning it was about 200 times farther away, 50 million miles vs a bit less than 1/4 million for the moon. Both objects were also at opposition that night, Dec 7/8, 2022, 180 degrees from the sun in the sky from Earth's point of view. The moon is full at opposition (the very definition of truly full), planets farther from the Sun are basically closest, biggest and brightest during opposition. The Sun, Earth, moon and Mars were all in a straight line in space that night, an event called syzygy.

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darrellbear t1_jbcu1vt wrote

AKA sunbeams, aka crepuscular rays. If you ever see crepuscular rays when you look at the sunset, turn around and face the opposite direction. You may see dark counterparts, known as anticrepuscular rays. They're the shadows of the clouds causing the sunbeams in the west. Anticrepuscular rays converge on the eastern horizon, opposite the sun's position in the west.

https://apod.nasa.gov/apod/ap200318.html

https://apod.nasa.gov/apod/ap160627.html

The same holds at sunrise, of course.

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darrellbear t1_ja1c41k wrote

Conservation of angular momentum--the moon's tidal effects on Earth are transferring the Earth's angular momentum to the moon. The moon speeds up as a result, which causes its orbital distance from Earth to increase over time. The Earth's loss of angular momentum causes it to spin on its axis more slowly, increasing the length of day over time. Total energy of the system is conserved.

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darrellbear t1_j8ps4g0 wrote

Northern hemisphere winter happens when the Earth is relatively close to the Sun in its orbit, so we have that going for us. Winters would be colder and summers hotter if we were farther from the Sun during our winter.

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darrellbear t1_j7bfn4i wrote

You have that backwards--the farther north the shorter the daylight during winter. Cross the arctic circle in winter, the sun doesn't rise at all. Conversely, during summer, the farther north the longer the daylight. Cross the arctic circle, the sun doesn't set at all during summer.

The same applies in the southern hemisphere, of course.

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darrellbear t1_j6zw1mq wrote

Dobsonian telescopes will give you the most bang for your buck. I'd say a 6 inch aperture at a minimum for an adult. An 8 inch will get you years down the road. The sky's the limit from there. DO NOT BUY A DEPARTMENT STORE TELESCOPE, they're junk. Orion Dobs are well regarded:

https://www.telescope.com/

A caution: like so much nowadays, telescope prices have risen a lot. You should get an extra eyepiece or two of various focal lengths, that's how you change magnification. You can also get a Barlow lens, which multiplies focal length by 2X or 3X. Telescopes and astronomy are a vast subject, barely scratching the surface here.

One of the best things you can do--find your local astronomy club, go to a meeting. They often have public star parties, attend some. The members are happy to show off their equipment and to answer questions. Learn about different types of scopes, it will help you make an informed decision when it's time to buy.

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darrellbear t1_j53rilg wrote

Some constellations are ancient, such as Scorpius, going back thousands of years. People used to put their stories in the skies. Shamans and night watch came to know the sky, noticed changes like planetary movement, the sun, moon and such, and sought meaning in what they saw. Learning when to plant crops came from observing the skies.

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darrellbear t1_j478h5t wrote

Get a torque wrench of the appropriate range (in/lbs, ft/lbs, etc), set it to the desired amount and tighten the screw/s. The wrench will let you know when you've reached the setting--it will click, release, illuminate or such. Specific tightening techniques can be required for certain applications such as engine head bolts, wheels, etc.--bolts may be required to be tightened in a certain order/pattern/amount, multiple passes, etc.

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darrellbear t1_j44ei30 wrote

Hydrogen emission is red. Oxygen is blue-green. These are true colors and make up the bulk of emission. Other elements do produce colors, neon is red too, for instance. Emission happens when gases are ionized and then recombine--excited electrons leave the atoms, then rejoin. Photons of characteristic color/energy are released upon recombination, hence the red of hydrogen and blue-green of oxygen. Hydrogen is common in "stellar nursery" nebulas, hence they're mostly reddish. Planetary nebulas often show a lot of green due to doubly ionized oxygen.

The so-called Hubble palette is actually false color, produced with narrowband filters--sulfur is shown as red, hydrogen as blue, oxygen as green.

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