Full moon vs sun?

We get a full moon once a month, which is kinda special. But is there a sun equivalent of getting a full moon? Where once and a while the sun does something different? 

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  • Clive
    Lv 7
    1 month ago
    Favourite answer

    No.  Full Moon is the result of the Moon having phases as it orbits Earth.  The Moon doesn't emit its own light, we can only see sunlight reflected off it, and how much of it is lit up by sunlight changes as it moves round once a month.  Full Moon is when it is directly opposite the Sun in the sky so the whole side facing us is lit up.

    The Sun doesn't have phases because it makes its own light, We can always see the whole disc every day.

    But for something else caused by the Moon orbiting Earth once a month, there are eclipses.  The Moon's orbit around the Earth and the Earth's orbit around the Sun aren't exactly lined up, they're angled about 5 degrees apart,  So normally at New Moon, you just can't see the Moon at all because the back is lit up, and at Full Moon, you see a full Moon because the Earth isn't in the way.

    But the orbits cross at two places, called the nodes.  If it is New Moon at a node, then the Sun, Moon and Earth are lined up in a dead straight line.  The Moon casts a shadow on the Earth, and if you're standing in the shadow, the Sun is blocked out.  That's a solar eclipse.  The shadow is only a few miles wide so you have to be in the right place to see it, so people will travel for miles to see it, and it only lasts a few minutes before the Moon moves on.  Quite a sight to see so it excites people.

    For something easier to see from home, there are lunar eclipses. If it is Full Moon at a node, then the Moon will pass through the shadow the Earth casts in space.  This takes a few hours because the Earth casts a shadow that is bigger than the Moon at this distance (after all, it IS bigger than the Moon), and it just happens to need to be night where you are to be able to see it.  So half the world can see it.

    You'd think the Moon disappears but it doesn't.  The Earth has an atmosphere, and that bends the sunlight.  Remember that sunlight can be refracted to make a rainbow from red through to blue.  Red light gets bent most, it gets bent far enough to land on the Moon, so the Moon doesn't get blocked out completely, instead it turns a dim coppery-brown.  So some people call it a blood moon.

    Of course all this is completely predictable.  Assuming you're American, then according to https://www.timeanddate.com/eclipse/list.html , the next total lunar eclipse visible where you are is likely to be the one on 26 May 2021, If not, the one on 16 May 2022 will be better.  I've ignored penumbral eclipses because you'll hardly notice anything happening.

  • 1 month ago

    Every year, the Sun appears ever so slightly larger than average when Earth is closest to it (perihelion) in January, and ever so slightly smaller than average when Earth is furthest from the Sun (aphelion) in July.

    The difference is not much (0°32.6' vs 0°31.7')

    Still, it is sufficient so that the totality portion of solar eclipses that take place in July will (on average) last a bit longer than total solar eclipses taking place in January.

    Because of Earth's rotational tilt (compared to our orbital plane), the Sun's declination reaches a northerly maximum in late June (solstice) giving people in the northern hemisphere more daylight hours and it reaches a southerly maximum in late December, giving northerners much shorter days of sunshine. That is the cause of seasons in the temperate and arctic regions.

    The Sun also has a "somewhat-around-11-year" cycle of sunspots, with a maximum number of sunspots and a minimum number of sunspots. If you take into account the direction of the magnetic field connected to the sunspots, then the total cycle is somewhat around 22 years.

    I say "somewhat" because the duration can be very irregular. It is not like clockwork.

    Of all the above, only the seasonal change in declination is readily apparent to onlookers.

  • 1 month ago

    The full moon is something we only see once per month as the moon orbits the Earth... the sun we see pretty much the same every day because we rotate. 

    There *are* special days - the equinoxes, where the day and night are about the same length, and the solstices, when the sun is at it’s furthest north or furthest south in our sky.  And, the occasional eclipse, when the moon crosses in front of the sun, blocking some or all of it’s light for a few minutes to a few hours.

  • 1 month ago

    No. The sun does not have phases because the sun is not reflecting light from a central body. It is the central body. 

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  • 1 month ago

    Solar eclipses at new Moon. We recently had one, but it was visible in North Africa India and Asia.  There will be a penumbral lunar eclipse at full Moon.

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