Daily we see the whole celestial sphere make one complete rotation around the Earth, or rather we see Earth make one complete rotation inside the celestial sphere. That is why we see the sun and stars move across the sky during a day/night. During a day, the Sun actually stays relatively still compared to the stars. Meanwhile, in one year the Sun makes one complete circle across the celestial sphere. That circle is called the ecliptic, and it has an inclination of around 23.5 degrees compared to the celestial equator. This means that the Sun crosses the celestial equator twice a year, once northbound and once southbound, this is of course exactly where the ecliptic circle and the celestial equator circles intersect. The vernal equinox is the point where the Sun crosses the celestial equator northbound. At that time when the Sun is crossing the equator, we also experience equal length night and day. This is where the name comes from. So the equinox is really a point in the sky where the Sun is located at the time of year where we have even night and day (which is twice a year.) In ancient history the northbound equinox was called the first point of Aries, because that is where it was located. We now know that the ecliptic circle is slowly rotating (this is called precession) around the celestial poles, with a period of around 26000 years. So the equinox is no longer in Aries. That is also what gives rise to "the age of Aquarius" from the somewhat famous song, which refers to the fact that the vernal equinox point will be entering the constellation of Aquarius around year 2100. Although the equinoxes are two points in the sky, outside astronomy we often refer to the equinoxes as the time during the year where the Sun is located at one of those two points. Really, these are two instants of time, but we often talk about them as a day because those are the days where everyone outside the arctic circles see day and night being of equal length. This is why it is a bit confusing, we regular people talk about a moment in time, but astronomers talk about a point in the sky. I know you asked this more than a month ago, but thought that others may have the same question.

@marilyn rogue Hobby. Instead of measuring right ascension like astronomers, celestial navigators measure leftward from Greenwich (prime meridian) and call it the Greenwich Hour Angle (GHA) and measure in degrees, not hours. For example, if it’s local noontime where you are (by seeing when the sun peaks in the sky (culminates)) and your wristwatch which is set for the time at Greenwich says 1pm then you are at 15 degrees west longitude (more or less). I’ve wanted a celestial sphere model, but they are overly pricey. Thanks for your efforts.

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No.only northern sky will be visible to them.

You can see 90 north and south of you!(as well as East and west of you). I live at about 40 N latitude so I can see stars down to 50 degrees south. Think of the sky like a big half dome or umbrella above you. The stars directly above you is the center of the dome and you can see 90 degrees in all directions (the edge of the umbrella would be at the horizon). The only place you could be located where you wouldn’t be able to see any of the other hemisphere would be if you were located exactly at the N or S poles.

Yes, one may--partially. For example, I live +30 degrees north of the celestial equator. Hence, I can see a number of Southern Hemisphere celestial objects. For example, I can see the constellations of Scorpius and Sagittarius which are Southern Hemisphere constellations. It is not only the few Southern Hemisphere constellations that I can see, but with a telescope, I can observe many beautiful celestial Messier objects, such as M8, M17, M18, M20, M21, M22, M23, etc. I can also see the magnificent Omega Centuri Globular Cluster (a cluster of about 10 million stars) low in the Southern Hemisphere from mid-June to early July. However, because of Earth's curvature, I would have to travel southward to see more of the stars in the Southern Hemisphere. This is also true for those who live nearer to the Equator. They can see some of the stars in the Northern Hemisphere too. The Orion Constellation lies on the Celestial Equator and is visible throughout most of the world from mid-October to early Spring. As I travel southward, the stars that look lower on the southern horizon where I live would appear to move higher above me. Every degree I move southward, one more degree of the height of the Southern Hemisphere stars that I may see (if all things are equal). However, each degree I travel southward is in direct proportion that the Northern Hemisphere stars set below my northern horizon. So, if I travel 5 degrees further south, the stars would appear to rise 5 degrees more. If I turned around and looked northward, I would notice that the stars would have appeared to be 5 degrees lower, with stars disappearing in the north in direct proportion to my latitude. Once I reach the equator, I would no longer be able to see the North Polar Star, Polaris, while looking northward. For the celestial equator is 0 degrees, hence, Polaris is 0 degrees at my northern horizon. Many barge captains have told me that one must be a few degrees north of the equator to see Polaris on the low northern horizon because of the Earth's bulge. I take their word on the matter, for they are very skilled in using the Sextant instrument and they have traveled extensively between the Northern and Southern Hemispheres.

Would you like to bet a few grand that it doesn't?

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@@luismerchan9140 corona on dec 26 than dec 31. They tell us. This is just the beginning. Phase 2 starts 10/10/2020. Event 201 on 10/18/19 plus 11m22days is 10/10/2020. Its also 6969days after 9/11/01 969w6days after the 1st light up of the 88 lights at ground zero 969days after Parkland school shooting I can go on and on. Event 1122

My avatar is the Storm Kansas Point of "KNOW" return album cover. Released 10/11 Trump dad birthday 10/11 1101 days after Trump said its the calm b4 the Storm Bush sr died 11/30/18 at 22:10 Adding 22m10days is 10/10/2020 Adding 1y10m10days is 10/10/2020 (Another 1101) like flipped 9/11/01 gets you 1011 and 6from9. Top of freemasonic arch is ♋. They tell us. Corona is the ring around the sun Floyd hoax was on the 93rd meridian as in 93mill mile sun lmao. Sun coding/rituals, but the sleeping masses just cant grasp it. 1011 is not a prime has factorization of 3x337=1011 Adding 3y337days from Trumps election win on 11/8/16 takes ya to 10/10/2020 Phase 2 starts in Oct 2020

Cringe