# Tag Info

14

You must have misheard it, or the documentary you watched wasn't presenting very precise information. It does set but it also stays on the night sky for several days during the polar winter (polar night) when the Moon if full. This is relatively simple to imagine, so I'll describe it; So what's happening is that the Earth's axial tilt during the polar ...

7

You are mixing the rotation of the body around a barycenter with its moons, and the rotation of the body around its own center. For a bound rotation like Pluto and Charon both have to have the same rotation period - yet both have to be present. Thus Pluto's axis of rotation of course intersects its surface - it rotates around its own axis at exactly the same ...

6

The article you've read is not quite accurate/correct. A more correct pictue is as follows: A star may approach a super-massive black hole (SMBH) so closely that the tidal forces of the SMBH tear it appart. The distance to the SMBH at which this happens is often referred to as the tidal radius. For a (non-rotating) SMBH with a mass in excess of about $10^8$...

5

I'll just add a supplement to @planetmaker's answer. As long as a body is distinct and not connected to anything else, it will have a center of mass. If the body is roughly spherical its center of mass will be near it's middle. The body's rotational axis by definition passes through its center of mass, and is parallel to it's own angular momentum vector. If ...

5

Does Polaris have a trail in the sky timelapse? Yes. Every star has a trail, but it's smaller if it's closer to the pole. Polaris is close to the pole but it's still 45 (arc)minutes away. I don't think it's visible with the naked eye; no star trail is visible with the naked eye as you only see one 'instance' of the sky. What perhaps would work, and is more ...

5

For the practical side of TidalWave's excellent answer, here's a moon almanac for the place: http://www.timeanddate.com/moon/norway/longyearbyen In 2014 the moon is above the horizon for a maximum of about 9 days at a time.

3

If you assume that the shift was due to natural process, it would still point more-or-less towards Polaris. (If the shift is due to magic or advanced technology, all bets are off.) I think your question may be based on a false premise, that the celestial sphere is fixed relative to the Earth. It isn't at all. Over the timescales we're dealing with it's ...

3

Polaris is about 1 degree from the celestial North Pole. An image with sufficient magnification and sufficient exposure time will show a (short) trail for Polaris. The difference between the images is the magnification and the exposure time and Magnification. The first image appears to have been about 10 hour exposure (actually a multiple exposure) The Last ...

3

That was a curiosity that I also had once. The reason for that is that the magnetic pole near earth's geographic north pole is actually the south magnetic pole. You can find a more detailed answer on https://wtamu.edu/~cbaird/sq/2013/11/15/why-does-a-magnetic-compass-point-to-the-geographic-north-pole/ Happy Thanksgiving!

3

Let my try to stretch the analogy to anticyclonic tornados: The vast majority of all tornados move cyclonic, i.e. counterclockwise on the Northern Hemnisphere of our blue planet. There is e.g. a publication on anticyclonic tornados by Howard Bluestein et. al. which says: It is also possible that the source of vorticity in the anticyclonic tornadoes is not ...

3

Here's a NASA movie showing Libration: http://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4000 As given in the details here, the position angle is the angle between the Moon's north and celestial north. This changes because of the inclination of ecliptic to equator + inclination of moon's orbit to ecliptic and plus, there might be some contribution from the ...

3

I have made an interactive simulation of Uranus and its seasons at https://ecliptiqc.ca/UranusEN.php. Playing with it, I get the north pole of Uranus pointing sunwards in early 1946 (my steps are 6 months, so I can’t be more precise for now). The actual date may be slightly different, as I use a “fixed” orbit instead of the osculating elements, but it would ...

2

According to JPL HORIZONS, the sub-solar latitude on Uranus has maxima on 1946-04-03 and 2030-04-11, and Uranus's heliocentric J2000 ecliptic longitude at those times is 77.54°. If I put the pole coordinates from the IAU WGCCRE report through the NED coordinate calculator, I get a J2000 ecliptic longitude of 77.65° for Uranus's south pole. The solstice ...

2

The "small vibration" is Libration, and it does not imply that lunar axis changes orientation. It is caused by Moon's movement not being a perfectly circular orbit parallel to Earth's Equator with aligned axis. Here's a description of the causes of libration from the Royal Observatory (check the linked page for graphics of each source): ...

2

Collecting and reporting the requested information is the job of the IAU Working Group on Cartographic Coordinates and Rotational Elements. They issue reports every few years; the most recent report was in 2009. The report is currently available at usno.navy.mil and astrogeology.usgs.gov, and elsewhere. Table 1 provides data for the Sun and planets (...

2

In Miami, Polaris will be approx 25 degrees above the horizon, not 65. Height above the horizon is equal to the latitude of the observer. At the North Pole, Polaris is very nearly directly overhead, all the time, because the Earth's axis of rotation points very nearly towards it. Due to precession, Polaris will not always be so close to where the Earth's ...

2

That's a timelaps video, most likely created from a sequence of photos. It's easy to choose sensitivity and ISO settings on normal cameras such that the night sky at the darkest night is over-exposed. The moon light looks like sunlight - as it simply is reflected sunlight. E.g. see https://cloud.planetmaker.de/index.php/s/yJ7AXWG4dEC6csW - it's a an exposure ...

1

tl;dr: You are seeing Astronomical twilight growing brighter through the month of August 2017 at the south pole! For more on the Moon's motion see the excellent answer to How does the Moon move in the "night" sky as seen from the poles? Here are two screenshots and a calculation of the altitude and azimuth of the Moon and the Sun throughout the ...

1

Geographic Meridian Every point on Earth is on some meridian: A (geographical) meridian (or line of longitude) is the half of an imaginary great circle on the Earth's surface, terminated by the North Pole and the South Pole, connecting points of equal longitude, as measured in angular degrees east or west of the Prime Meridian. From where you are standing, ...

1

Many of the moons of Jupiter and Saturn are tidally locked and probably move ice from their equatorial regions to their polar regions. Ganymede is the best example where you see bright polar ice caps and a dark equatorial zone. A migration process occurs on all of these moons in which light from the sun gets absorbed by water ice molecules and sends them on ...

1

Why does the Moon never set in Svalbard, Norway? Source As can be deduced from the diagram or knowing that the Moon's orbit is inclined by only 5 degrees with respect to the ecliptic while the Earth's axis is inclined by more than 23 degrees, the moon can not always be above the horizon, nor always be below it. Over the course of about 20 years all ...

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