New answers tagged earth
2
Yes... in some ways.
The "flames" you can are not like flames from a fire on Earth. They are strongly connected to the magnetic field. The flames are called "prominences" and are composed of loops of plasma following magnetic field lines. A prominence is big, it can reach 800,000km from the sun's surface, but since the Earth is 150,000,...
4
The "tongues of flame" I think you're referring to are solar prominences:
They can reach heights above the Sun's surface (actually, photosphere) of around 100,000 km (Hyperphysics). The distance to the Sun is around 150,000,000 km. No, they can't reach Earth. However, every now and then the Sun does emit much larger, localised bursts of plasma and ...
6
There are two types of angular momentum of each planet: orbital angular momentum of the planet around the Sun, and rotational angular momentum of the planet around its rotational axis.
Orbital angular momentum $L_{orb}$ is typically calculated at perihelion or aphelion as $L_{orb}=mvr$, where $m$ is the mass of the planet, $v$ is the instantaneous orbital ...
3
Due to the fact that electrons can escape the gravitational field of the sun more easily than ions, the sun is positively charged by an amount $q=77$ Coulombs (see https://www.aanda.org/articles/aa/abs/2001/24/aah2649/aah2649.html ). You can calculate the Lorentz force from this. The magnetic field of the Milky Way is however even much smaller than 1/1000 of ...
2
The diagram from Astronomy magazine is correct; the book excerpt is a little confused.
Winter solstice is not when the Sun appears opposite certain stars, but when the Sun appears farthest from the Earth's north pole.
The time-dependent difference between these is due to axial precession.
There are several different definitions of a year:
Name
Mean Length
...
6
The book is incorrect. The calendar is designed to keep track of the seasons. What will happen in 13000 years is that the Northern Hemisphere summer solstice will still occur near the end of June, but it will occur near perihelion rather than near aphelion. In 13000 years, summers in the Northern Hemisphere will be short but intense, and winters will be both ...
5
Yes, "future perihelic oppositions will bring Earth and Mars even closer."
No, in the long term (after about 25000 years), Mars's eccentricity will start to decrease, and then perihelic opposition will not be as close.
By frankuitaalst from the Gravity Simulator message board. - Data generated with Gravity Simulator written by Tony Dunn.Source JPG ...
4
In actual fact its a bit more complicated, because
the Earth's orbit is not perfectly circular,
The star does not lie exactly on the Earth's orbital plane, so the observation is not a line of movement but an ellipse
both the Sun and the Star are moving relative to everything, so the ellipse is not an ellipse but a helix
Observational errors from various ...
3
You measure it on the photographs.
If you take multiple images of the same star over the year you will find that it moves in a loop (compared to the very distant background stars) You measure the size of the loop. A larger loop is a larger angle. Because the angles are small, the size of the loop is in direct proportion to the angle. If you know the scale ...
6
Second question first:
If the emitted power is the same does it matter if the emitting body is a large sphere of gas or a solid sphere?
Not really. For thermal radiation discussed below, as long as the emissivity is high at the wavelength in question, it will radiate similarly to a blackbody. We see light from the Sun's photosphere which is roughly where ...
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