Earth

The Earth is a planet in the Solar System, orbiting Sol. Earth is the only known planet capable of supporting life, containing water, reasonable levels of oxygen, and a stable temperature range. Geometrically speaking, Earth is the largest of the terrestrial (rocky) planets in the solar system.

People disagree about when and how the Earth was created. The three most popular ideas are:

1. That God created the Earth several hundred generations ago, as recounted in Genesis. By adding years and other time indications in the Old Testament chronologies, one can calculate the age of the Earth as approximately 6,000 years (see Date of creation and Young Earth Creationism).
2. That God created the Earth billions of years ago (see Old Earth Creationism).
3. That the Earth came into existence billions of years ago, but entirely through natural processes and without any intervention by God

Clashes between adherents of these ideas have gone on since time immemorial (see origins debate), though the last theory has only been fully developed in the last 200 years.

Physical Description

Within the solar system, Earth is the third planet from the Sun. It is approximately 8,000 miles (13,000 km) in diameter, which means that its equatorial circumference (measured around the equator) is 24,901 miles (40,075 kilometers), and the polar circumference is slightly less at 24,809 miles (40,008 km).[1] The reason its metric circumference is so close to the "round number" of 40,000 is that the kilometer was defined (by the French) as 1/10,000th the distance from the equator to the North Pole.

Its surface area is approximately 4·π (4000 mi)² = 200 million square miles (510 million km²). It has been said that Earth should really be called "water", as the larger part of it—about 70%—is covered by water. In fact, the Pacific and Indian oceans alone cover about half of the Earth's surface.

The Earth orbits at an average distance of about 93 million miles (150 million km) from the Sun in an almost circular orbit. It takes light (and other forms of electromagnetic radiation) approximately 500 seconds to travel from the Sun to the Earth, i.e. the distance can also be stated as "500 light-seconds." The distance to nearby stars is made by measuring the stellar parallax between observations when the earth is at opposite ends of its orbit, so the earth's orbit itself is a measuring stick for astronomical distances, and is known as the astronomical unit (A. U.) It is worth noting that if the Earth were slightly closer to the Sun, it would be too hot for life (just as Venus is) while if Earth were slightly further away from the Sun, water would freeze and life would be impossible.

Young Earth Creationist view

Formation and Age

So far scientists have not found a way to determine the exact age of the Earth directly from Earth rocks because Earth's oldest rocks have been recycled and destroyed by the process of plate tectonics. If there are any of Earth's primordial rocks left in their original state, they have not yet been found. Nevertheless, scientists have been able to determine the probable age of the Solar System and to calculate an age for the Earth by assuming that the Earth and the rest of the solid bodies in the Solar System formed at the same time and are, therefore, of the same age.

The ages of Earth and Moon rocks and of meteorites are measured by the decay of long-lived radioactive isotopes of elements that occur naturally in rocks and minerals and that decay with half lives of 700 million to more than 100 billion years to stable isotopes of other elements. These dating techniques, which are firmly grounded in physics and are known collectively as radiometric dating, are used to measure the last time that the rock being dated was either melted or disturbed sufficiently to rehomogenize its radioactive elements.

Ancient rocks exceeding 3.5 billion years in age are found on all of Earth's continents. The oldest rocks on Earth found so far are the Acasta Gneisses in northwestern Canada near Great Slave Lake (4.03 Ga) and the Isua Supracrustal rocks in West Greenland (3.7 to 3.8 Ga), but well-studied rocks nearly as old are also found in the Minnesota River Valley and northern Michigan (3.5-3.7 billion years), in Swaziland (3.4-3.5 billion years), and in Western Australia (3.4-3.6 billion years). [See Editor's Note.] These ancient rocks have been dated by a number of radiometric dating methods and the consistency of the results give scientists confidence that the ages are correct to within a few percent. An interesting feature of these ancient rocks is that they are not from any sort of "primordial crust" but are lava flows and sediments deposited in shallow water, an indication that Earth history began well before these rocks were deposited. In Western Australia, single zircon crystals found in younger sedimentary rocks have radiometric ages of as much as 4.3 billion years, making these tiny crystals the oldest materials to be found on Earth so far. The source rocks for these zircon crystals have not yet been found. The ages measured for Earth's oldest rocks and oldest crystals show that the Earth is at least 4.3 billion years in age but do not reveal the exact age of Earth's formation.

The best age for the Earth (4.54 Ga) is based on old, presumed single-stage leads coupled with the Pb ratios in troilite from iron meteorites, specifically the Canyon Diablo meteorite. In addition, mineral grains (zircon) with U-Pb ages of 4.4 Ga have recently been reported from sedimentary rocks in west-central Australia.

The Moon is a more primitive planet than Earth because it has not been disturbed by plate tectonics; thus, some of its more ancient rocks are more plentiful. Only a small number of rocks were returned to Earth by the six Apollo and three Luna missions. These rocks vary greatly in age, a reflection of their different ages of formation and their subsequent histories. The oldest dated moon rocks, however, have ages between 4.4 and 4.5 billion years and provide a minimum age for the formation of our nearest planetary neighbor.

Thousands of meteorites, which are fragments of asteroids that fall to Earth, have been recovered. These primitive objects provide the best ages for the time of formation of the Solar System. There are more than 70 meteorites, of different types, whose ages have been measured using radiometric dating techniques. The results show that the meteorites, and therefore the Solar System, formed between 4.53 and 4.58 billion years ago. The best age for the Earth comes not from dating individual rocks but by considering the Earth and meteorites as part of the same evolving system in which the isotopic composition of lead, specifically the ratio of lead-207 to lead-206 changes over time owing to the decay of radioactive uranium-235 and uranium-238, respectively. Scientists have used this approach to determine the time required for the isotopes in the Earth's oldest lead ores, of which there are only a few, to evolve from its primordial composition, as measured in uranium-free phases of iron meteorites, to its compositions at the time these lead ores separated from their mantle reservoirs. These calculations result in an age for the Earth and meteorites, and hence the Solar System, of 4.54 billion years with an uncertainty of less than 1 percent. To be precise, this age represents the last time that lead isotopes were homogeneous througout the inner Solar System and the time that lead and uranium was incorporated into the solid bodies of the Solar System.

The age of 4.54 billion years found for the Solar System and Earth is consistent with current calculations of 11 to 13 billion years for the age of the Milky Way Galaxy (based on the stage of evolution of globular cluster stars) and the age of 10 to 15 billion years for the age of the Universe (based on the recession of distant galaxies). >

Shape of the Earth

Some Young Earth Creationists and Biblical literalists also dispute the shape of the earth, saying that according to the Bible, the earth is flat rather than spherical (presumably square, given that it is described as having "four corners" (Revelations 7:1)). However, no credible organization has ever expressed support for this theory. Some Biblical literalists also dispute the idea that the earth rotates around the sun.

In Revelations 7:1 it is stated:

"And after these things I saw four angels standing on the four corners of the earth..." (Revelations 7:1)

A sphere has no corners. The four corners are also mentioned in Isaiah 11:12. This is often accepted to be a figure of speech.

It is also stated:

"Then was the iron, the clay, the brass, the silver, and the gold, broken to pieces together, and became like the chaff of the summer threshingfloors; and the wind carried them away, that no place was found for them: and the stone that smote the image became a great mountain, and filled the whole earth." (Daniel 2:35)

AND

"Thus were the visions of mine head in my bed; I saw, and behold a tree in the midst of the earth, and the height thereof was great. The tree grew, and was strong, and the height thereof reached unto heaven, and the sight thereof to the end of all the earth:" (Daniel 4:10-11)

AND

"Behold, [Jesus] cometh with clouds; and every eye shall see him" (Revelations 1:7)

AND

"Once again, the devil took him to a very high mountain, and showed him all the kingdoms of the world [cosmos] in their glory." (Matthew 4:8)

Apologist JP Holding's take on this is that this may have been a vision.

Position of the Earth

In the view of the Bible the Earth is fixed, and the sun revolves around it. This can be found in several passages:

"He has fixed the earth firm, immovable." (1 Chronicles 16:30)

"Thou hast fixed the earth immovable and firm ..." (Psalm 93:1)

"Thou didst fix the earth on its foundation so that it never can be shaken." (Psalm 104:5)

"...who made the earth and fashioned it, and himself fixed it fast..." (Isaiah 45:18)

See Also: Geocentric theory

Christianity and the Earth

Christian Literalism

Bible scholars have estimated the age of the earth based on the Creation account in Genesis and the genealogical accounts in Numbers and other books of the Pentateuch. One famous estimate was published in 1650 by James Ussher Archbishop of Armagh in a book called Annals of the World, in which he estimated the Creation to have occurred on 23 October 4004 B.C. Other Biblical scholars maintain that there are possible gaps in the genealogies, often using the ideas of the 19th century Calvinist theologian Benjamin Warfield on the issue. However, James Barr, regius professor of Hebrew at Oxford University, wrote in 1984 the following: "… probably, so far as I know, there is no professor of Hebrew or Old Testament at any world-class university who does not believe that the writer(s) of Genesis 1–11 intended to convey to their readers the ideas that: … the figures contained in the Genesis genealogies provided by simple addition a chronology from the beginning of the world up to later stages in the biblical story.’" Furthermore, it should be noted that Barr himself rejects supernatural Christianity, and so is not a priori biased in favor of creationism.

Many Christians believe that the Earth is the perfect distance away from the Sun and take this to be evidence of God's existence. Secular scientists, however, reject this reasoning using the anthropic principle.

Christian Non-Literalism

Many mainstream Christian denominations believe the story of Genesis is not meant to be read literally, and believe that the age of the Earth is on the order of millions or billions of years, not thousands of years.

Scientific Uniformitarianism

Uniformitarian scientists believe that the earth is beyond 4 billion years old. They also refute that the Earth is only 6,000 years old by quoting older human societies dated by their dating method as older than that.

Evolutionary view

Estimates by geologists of the age of the Earth give about 4.55 billion years. This estimate is primarily based on radioactive dating of meteorites. The extreme majority of scientists conclude that the Earth formed by natural processes, specifically by the accumulation of debris orbiting the sun billions of years in the past. Indeed, astronomers have detected dust lanes around other stars that indicate planet formation is a common and ongoing process.