as far as the Universe goes. You have heard of a supernovae (9), there will simply not be enough mass to our Sun's core left to hold the gases together and go supernovae, or as stated, to become a helium star. It has been estimated by most cosmologist that a star, such as our Sun, would have to be between one point three to three times its mass in order to go supernovae (most likely the Sun would have to be at least four times its current mass to go supernovae).
As stated, because our Sun is but a small star, the resulting mass of helium (at the end of its main sequence life cycle) will not have enough pressure (gravitational force) to begin the fusion process and become a helium star, or go supernovae, instead the Sun will pretty much go out in a whimper as a red giant (7).
As the hydrogen atoms are exhausted, the small helium core left will not have enough gravitational mass to hold the hot gases surrounding it, a red giant is formed as the surface gasses and radiation will simply wander in an ever expanding bubble until these gasses finally dissipate into space. The expansion of the hot gasses and radiation will envelope the four innermost planets (maybe not Mars, too, close to call) and these planets also will be absorbed back into the Universe, back to the elementary properties they were created from as they are incinerated in the hot gasses and radiation of the dying Sun.
To reiterate, a supernovae is caused by the tremendous gravity of a large dense core that does not let any of the gasses and radiation escape, gravity overwhelming electromagnetic force. As these molecules are all pulled into a very small compact ball at the center of the star, the heat generated with the tremendous pressure of the compaction (most believe this how the Big Bang occurred) will cause it to not ignite the nuclear furnace, but rather to eventually explode because of the tremendous gravity at the core, emitting vast amounts of radiation and scattering its molecules throughout space, what is usually left behind after a star goes supernovae is a small core called a white dwarf (10).
From the very first star, this scattering of radiation, molecules and new elements created within that first star going supernovae is what gave diversity to the infant Universe.
Our Sun, when it is a red giant, will still release tremendous amounts of radiation as it continues to die and is typical of a hydrogen star of this size. As stated, this release of radiation will flow throughout all of the Universe as it is meant to do, replenishing and nurturing the life of the Universe, eventually giving birth to new celestial bodies and physical matter. When the outer gasses are finally exhausted, the Sun's left over core will be no more than a small cold mass of helium and carbon atoms, these also will eventually dissipate (as it cools over time) back into the mass that is the Universe.
Succeeding generations of stars created from these remnants create different elements as they, too, eventually live their life and return their basic and new elements to the vastness of the Universe. In fact, every molecule in your body originated from a once distant exploding star.
Living physical forms of life could not exist in the Universe without the death (life cycle) of the stars.
Although we appear to be surrounded by stars and our solar system is a part of the Milky Way Galaxy, the closest star to us, Proxima Centauri, is still about four point two light years away, that's more than 24.5 trillion miles. The brightest visible star in the night sky is Sirius, about eight point five light years away and is visible in the northern hemisphere. The vastness of the Universe is incomprehensible to the populous of this planet, what you see in the night sky is only a small part of the Milky Way Galaxy we reside in. There is just no way to properly explain how large the Universe is compared to the tiny world we live on.
THE TERRESTRIAL PLANETS
The closest plant to the Sun, Mercury, is a hot desolate 'rock'. The solar winds of the Sun have all but diminished the planet to just a rock with a thin dry dusty layer of silicates and other loose minerals on the surface. The surface of Mercury resembles that of our Moon, pockmarked from the numerous meteor strikes that have occurred over the life of the planet. There has been no volcanic activity or lava flows since its core cooled billions of years ago, thus leaving the pock-marked surface.
There is virtually no atmosphere on Mercury and the planet rotates on an almost zero degree axis, thus there are also no seasons. The hottest part of the planet (estimated at four hundred twenty seven degrees Celsius) is at the equator facing the Sun and the coldest (at minus one hundred seventy three degrees Celsius) is at the poles and the dark side facing away from the Sun. These conditions would not make Mercury a suitable environment for life as we know it (other than possibly simple bacteria). A year on Mercury is a quick eighty eight earth days around the Sun.
Mercury is about forty percent the size of Earth and is getting smaller all the time as the solar winds continue to rip at its surface. The orbit of Mercury is slowly diminishing in distance from the Sun, at some point in time (in the very distant future) its orbit will erode to the point that it can no longer evade the massive pull of the Sun. As its orbit does erode, the speed of the orbit around the Sun will increase dramatically as it nears the circle of doom (11). The planet will most likely be ripped apart by the Sun's gravity before it actually impacts the Sun though.
Venus is the second planet from the Sun and is the Earth's closest neighbor at just thirty eight million one hundred fifty thousand kilometers (at its closest) from Earth. As does Earth, Venus has a mostly solid iron core, a thick mantel made up primarily of silicate minerals, but only a thin crust (about thirty km thick, compared to Earths seventy km crust). The size and mass of Venus is very close to that of the Earth, only being slightly smaller than our planet. Other than the Moon, Venus (referred to as the Evening Star) is the brightest light in our night sky, capable of actually casting a shadow on Earth.
The atmosphere of Venus is comprised primarily (about 96%) of carbon dioxide, creating an extreme green house effect on the surface. The average temperature on Venus' surface is around four hundred fifty degrees Celsius, making it the hottest surface temperature of any of the terrestrial planets in the solar system. The atmosphere (cloud cover) rises to an altitude of over sixty five kilometers and obscures the planet's surface from Earthly observers.
Planetary probes have penetrated the atmosphere (1970, 1975 Soviet Union; 1990's United States) and revealed the surface of the planet to consist primarily of basaltic rock between two hundred million and eight hundred million years old. The surface of the planet is covered with volcanoes, although there is no evidence of current activity. The fact that all of the surface rock appears to be relatively of the same age, poses the possibility that almost all of the volcanoes erupted during the same time line and then all abruptly stopped erupting.
Since the early days of interplanetary exploration, Venus has been used as a 'sling-shot' for spacecraft. Engineers learned early on they could drastically increase the speed of space vehicles by doing a fly-by of the planet and use the planet's gravity to propel craft to other celestial bodies in our solar system at an increased speed, using much less fuel in the process.
Venus has an anomaly with characteristics similar to our Moon in that it only shows one face to the Earth. Some astronomers believe this is caused by the Earth and Venus being 'tidally locked' at its closest approach to Earth, but is more likely just a circumstance of chance.
A day on Venus last for about two hundred forty three Earth days. This is in direct contrast to the length of a year on Venus (the time to orbit the Sun), just two hundred twenty five Earth days, so as you can easily see, a day on Venus last longer than a year on Venus!
Since the planet rotates on its axis (3 degree tilt) at such a slow rate, there is almost no magnetic field as the dynamo effect is virtually nonexistent. Another peculiarity of the planet is the fact that the planet rotates in the opposite direction of its motion around the Sun. This means the sun rises in the West and sets in the East, just the opposite of all other planets in our solar system. Some astronomers believe the planet to actual
ly be upside down, that is, the North pole is actually at the bottom of the planet. Astronomers believe this may be the result of a catastrophic collision during the formation of the solar system.
Because the planet rotates at such a slow speed, there is virtually no distortion at the equator, as is typical of other celestial bodies in our solar system. The circumference of the equator is almost exactly that of the poles, making Venus the most perfect sphere of all the celestial objects in our solar system. Venus also orbits around the Sun in an almost perfect circle (deviation of just .0070%) unlike the other planets, which have an elongated or elliptical orbit.
Earth is the third planet from the Sun. Of the billions of solar systems in the Milky Way Galaxy and the hundreds of billions of planets in our galaxy, there are only about twenty two thousand Earth-like planets that reside in a habitable zone, similar in makeup (although not identical) and climate to Earth. Currently, the closest habitable planet to Earth is about eight point five light years away, not far as the Universe goes, just across the street.
The three most important elements of a habitable or Earth-like planet are the