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Thank you. I prepare these of my students of a little background when we study certain topics. I am glad that other find them useful as well!

I hope you find the videos useful!

Thank you for taking the time to comment. In your model, with Earth-Moon ties together, we would also not have the Earth rotating. I would also suggest that observations made from any of the missions to the Moon would show that the Moon is rotating on its axis. In general, science would look at all models. If multiple models can explain one observation, we would look at what other predictions they make. Testing these predictions can distinguish between the models allowing scientists to select the one that bets fits the currently available data. Of course, models are always changing as new observations and findings are made that allow for them to become better refined.

@@introductiontoastronomy Thank you for your reply. I realise you must think I'm a bit dim but I can't get my head round it. As far as the Earth's rotation is concerned, I thought it could be discounted for this example, but if you like, I can refine my model. Imagine the tennis ball still glued to the rod but the other end has a ring which is placed over an 'axis rod' sticking out of the 'north pole' of the soccer ball. The rod holding the 'Moon' can now rotate freely, as can the 'Earth'. The tennis ball still cannot rotate. I really do not WANT to disagree with NASA, (or you) but the explanations I have been given so far do not help me.

Thank you! I think it is one of those things that gets in people's heads and becomes "truth" even when it is incorrect. Polaris is often talked about and one of the best known stars. However when someone (incorrectly) says it is the brightest, that can carry on and become accepted (say in lay culture - not in science!) So, people keep repeating what they have heard in the past with our bothering to actually find out if it is indeed, true.

I am glad that you find them helpful - I hope you do well in your class!

As I recall, if the Sun were orbiting Earth at its currently known distance, it would have to be traveling at a few percent of the speed of light.

Thank you for the information! I have seen many different variations in the last name and went with the one that seemed to be used most.

I am glad that you find these useful. I have prepared them for my own classes, but see no reason not to share them with others who may be able to use them as well!

Thank you for the comment and question. I have been reviewing my sources and am actually not sure where I got the three seasons. In Mapping Time (1998) by E.G. Richards it is suggested that there were only two seasons - each of six lunar months. These would be planting and harvesting seasons. I will have to review my work to find the reference for this - otherwise, I would have to consider my statement as unverified and possibly incorrect. I appreciate you mentioning the issue and bringing this to my attention!

That cannot be done in this simulator as you cannot make the masses of the objects the same. You will always have one more massive and one less massive object. You would need a simulator which allows you to have two objects of the same mass in circular orbits.

Not being an expert on this specific area, I cannot say for sure. My first thought is that we are looking at them differently. The Sun would be located in the direction of Virgo, Libra, and Scorpius in the fall which means that we would see them in the spring about six months later. The Chinese Azure Dragon may refer to when the constellations are visible, not when the Sun is located in that region of the sky.

This is a possibility. It is expected to either break apart or crash into the surface of Mars. This would likely not happen for tens of millions of years, however!

@@introductiontoastronomy (❗) =❓

You are correct - thank you for catching this. I did indeed state this incorrectly in the conclusion of the video. Declination is similar to latitude and Right Ascension is similar to longitude is the correct comparison.

From what I understand of the redefining there certainly were issues with the new definition and the process by which it was completed. However, it has become official policy of the International Astronomical Union (IAU) which is the body tasked with such definitions. My personal opinion is that Pluto does not below with the other eight major planets. It simply does not fit with these much larger objects. Although the IAU specifically excludes dwarf planets from being considered planets - this is something I disagree with. Why not have different classes of planets? We have eight major planets which are divided into separate classes. A dwarf planet could still be considered a planet, just a different class of planet. We also have other minor planets in addition to the dwarf planets such as asteroids. Part of the science here is the classification of these objects and finding out how they fit together. As more observations were made and we learned more about Pluto, we find that it really doesn't not fit with the eight major planets. As we learn more in science, we can (and should) change. There have been other objects in the past that were once considered planets and are no longer considered as such based on new information. Science constantly evolves and changes as new information is discovered. To answer your question - Eris is known to have at least one moon. Other dwarf plants are not known to have moons, but that does not mean that they do not have them. It means that they may not have yet been discovered. Also, having a moon is not a criteria for being a planet. If it were, neither Mercury nor Venus would be considered planets. And, several small asteroids which have moons would be considered planets.

Haumea has 2 moons Makemake has 1 Eris (more massive than pluto) has 1, as well several asteroids have been known to have moons.

Thank you for taking the time to comment here! The shift in parallax is measured relative to the background stars which are presumed to be so far away that they do not shit at all. The nearby star will appear to shift when viewed from two different locations. You can simulate this yourself by holding a finger in front of your face and alternately opening and closing each eye one at a time. Relative to the wall (distant stars) your finger (nearby star) will appear to change position. This is exactly what is meant by a parallax shift. As for the name parsec, you are correct it is the combination or two words. The parsec is the distance at which a star would have a PARalax of one arcSECond. Taking the PAR from parallax and the SEC from arcsecond gives us the parsec.

It must have a dense core. Gravity would pull down heavier elements and pressure would condense it too.

Yes, there would be a core of rock and metal several times the size of Earth. However, it would not be a solid surface in the sense of anything that could ever be landed on. The density and pressure of the gases in the atmosphere would be so high that one would not notice where the atmosphere ends and the "surface" begins!

Thank you for the comment. Yes, it would be good to have the distant background stars in the image. I was focused on finding an image that showed the parallax angle specifically. However, it does need to be measured with respect to the background stars for reference.

I appreciate you taking the time to comment. I do not consider myself to be an expert on comets. However, articles published as recently as 10 days ago (iopscience.iop.org/article/10.3847/1538-3881/acee59) in the Astronomical Journal show measurements of comet 67/P to be composed of icy materials including water, ammonia, and various hydrocarbons.

Thank you for taking the time to comment. I am glad that you enjoyed the video.

Thank you for the comment - I am glad that you are finding my videos useful!