Astronomy Questions?

Question

My sister needs help with her astronomy homework. I was wondering if any of you knew the answers so i could help point her in the right direction?

1. How do you think the seasons would be different if Earth were inclined 90 degrees instead of 23.5 degrees? 0 degrees instead of 23.5?

2.Are there other planets in our solar system from whose surface you could see a lunar eclipse? A total solar eclipse? Which ones and why?

Any help you could give would be greatly appreciated. And please if you dont know the answer or dont know how to get the answer please dont respond.

Answer 1

1. This is really two different questions, so I'll split it up.

1.1. If the Earth were inclined 90 degrees, then seasons would be very different. Around the time of the equinoxes, days would pass more or less normally, with the Sun rising and setting every 24 hours. However, around the time of the solstices (June 21 and December 21, approximately), the north or south pole (depending on the solstice) would be oriented directly towards the Sun, and the corresponding hemisphere of the Earth would be in constant daylight. During the transition from each equinox to the next solstice, the Sun would appear to inscribe smaller and smaller circles in the sky. Someone on the equator would see the Sun go from inscribing a complete circle passing right through the zenith (during the equinox) to making smaller and smaller circles towards one part of the sky, and finally coming to a stop right on the horizon, either directly north or directly south. Someone on the pole going to face the Sun would see the Sun go from moving around the horizon in a circle to rising into the sky and finally coming to a stop directly overhead. Someone the pole going to face away from the Sun would simply see the Sun, which would move around the horizon in a circle during the equinox, simply drop off across the horizon, causing several months of darkness (it would be darkest when the solstice was reached). The whole process would go backwards from that solstice to the next equinox, and then during the next half of the year would repeat both those stages, only going north instead of south or vice versa. Naturally, the implication of this is that the area experiencing summer would become extremely hot, while the area experiencing winter would become extremely cold; human civilization probably could not survive the resulting conditions.

1.2. This would make a much smaller difference than having the Earth tilted 90 degrees. Days would pass normally, every 24 hours, in every part of the world. However, the Sun would not move up and down in the sky with the passing seasons, rather it would always be seen inscribing the same circle in the sky from the same latitude on the Earth's surface. Seasons would exist, but they would be due only to the Earth moving slightly closer to and farther from the Sun during its orbit, and would have noticeably less of an effect than they do now (so temperatures would remain more constant for any given point on Earth, depending on the weather). Also, the seasons would heat and cool the entire Earth all at once, whereas right now the northern hemisphere experiences winter while the southern hemisphere experiences summer and vice versa.

2. You would be able to observe a total solar or lunar eclipse occurring on Earth from any planet in the Solar System, provided it was in the right position at the time and you were on the right side of it (and had a telescope capable of showing you an image of the Earth). However, you would not be able to observe a LOCAL total solar or lunar eclipse on any planet in the Solar System. Mars, Jupiter, Saturn, Uranus and Neptune all possess moons, so assuming you could see the moon in question from the planet and the moon had an orbit that took it 'behind' the planet relative to the Sun, you could see the moon pass into the planet's shadow, which would be a lunar eclipse. However, total solar eclipses are only possible where at least one of the planet's moons not only has an orbit taking it between the planet and the Sun but is also large enough to occlude the entire Sun at once. A total solar eclipse would probably be visible on Pluto since the Sun is so small as seen from Pluto, but you definitely couldn't see one on Mars (despite it having two moons), and my guess would be that probably none of the gas giants would have it either (if one of them did, it would probably be Jupiter; Titan is probably too far from Saturn to cause total occlusion of the Sun).

Answer 2

Your sister?  Well, okay then.

If the axis was inclined 90 degrees, the seasons would be catastrophically extreme. The equatorial regions would get cooler because the sun will range much farther north and south.  At the northern summer solstice, the north pole would be the hottest place on earth.  The south pole would be the coldest. Then that would reverse six months later.  The vast and relatively sudden differences in temperature would certainly cause storms like we have never seen. Almost all of the vegetation would die off, outside of the tropics because of weeks to months of almost total darkness. Huge numbers of species of animals would become extinct because of the drastic changes in environment.

If the axis was at zero degrees, we wouldn't have any seasons at all.  The tropics would become insufferably hot, causing widespread disaster.

You could see lunar eclipses from all the planets except Mercury and Venus.  From Jupiter, you would see moons moving into the planet's shadow nearly every day. The question about total solar eclipses is harder.  You have to consider the apparent sizes of the moons and the sun from the planets' distances outward.  For example, the sun might be so small from Neptune that Triton would be able to block it completely.  I'll check some of the others and get back to you.  (If I suddenly get 3 or more thumbs down, it is because someone has been sabotaging all my answers for three days now, using multiple accounts.)

Edit: Titan should be big enough to cause total solar eclipses on Saturn.  I know that some of Jupiter's moons can cause total eclipses because I have seen pictures of their shadows on the surface of the planet.  The shadows would not be nearly so dark if they were only partial eclipses.  Note: total solar eclipses would NOT be caused by every moon for every planet -- only partials and annulars.  *Total* solar eclipses are harder to figure.

As Mercury and Venus have no moons, they will not see any kind of eclipse.

Answer 3

1. Well, at 90 degrees, each hemisphere would get months of nothing but sun, followed by months of nothing but dark....

At 0 degrees, there wouldn't *be* any seasons - or not much, anyway, as everywhere on Earth we'd get 12 hours of day, and 12 hours of night.

2. Well, you could see lunar eclipses on Jupiter, Saturn, and Neptune;  A total solar eclipse would be an everyday occurance on Jupiter and Saturn - the planets are so big, that the moons *have* to eclipse the sun (and likewise, the orbit of the moon would take it through the shadow of the planet) on just about every orbit.  Also, the sun is so far away, that total solar eclipses are easy - as the moon appears much larger being so much closer to the planet.