If we had no moon then tides would fall, nights would be darker, seasons would change, and the length of our days would alter.
Although we likely would still survive without the moon but it does help with life.
If Earth had two moons it would be a bad thing and catastrophic.
Because if the earth had two moons or an extra moon would lead to larger tides and wipe out major cities like New York and Singapore.
And the extra pull of the moons would also slow down the Earth's rotation, causing the day to get longer.
The Moon is Earth's only natural satellite.
At about one-quarter the diameter of Earth, it is the fifth largest satellite in the Solar System, the largest satellite in the Solar System relative to its major planet, and larger than any known dwarf planet.
If Earth had two suns then the earth would likely be much hotter in the summertime and maybe warmer in the winter.
The two suns would probably appear to orbit each other roughly edge-on as seen from Earth, which would lead to a strange new phenomenon: an eclipse of the sun by another sun!
Because of the 10-day orbit, Sun 1 and Sun 2 would pass in front of each other every 5 days.
If the sun on earth went out then all the plants and animals as well as humans would eventually die out.
Not only do plants require the sun to survive but so do animals and humans.
As humans we get vitamins from the sun which we need to survive and without the sun we would not survive either.
Within a few days of the sun going out, however, the temperatures would begin to drop, and any humans left on the planet's surface would die soon after.
Within two months, the ocean's surface would freeze over, but it would take another thousand years for our seas to freeze solid.
In other words, it's extremely unlikely that life on any planet can survive the death of its sun but new life could spring from the ashes of the old once that sun shrivels up and turns off its violent winds.
So, the wind may be against us now, but one day it will be gone.
For us on earth, the sun is a source of life.
Even in Antarctica, the coldest place on our planet, temperatures seldom drop below minus 50°C.
Without the sun's radiation, the temperature would be anywhere near the absolute zero of minus 273°C.
Life would have never continued nor even have come into existence.
Earth has at least 1.5 billion years left to support life, the researchers report this month in Geophysical Research Letters.
If humans last that long, Earth would be generally uncomfortable for them, but livable in some areas just below the polar regions.
If the moon exploded, the night sky would change.
We would see more stars in the sky, but we would also see more meteors and experience more meteorites.
The position of the Earth in space would change and temperatures and seasons would dramatically alter, and our ocean tides would be much weaker.