Useful satellite data concerning sea ice began in late 1978 with the launch of NASA's Scanning Multichannel Microwave Radiometer (SMMR) satellite.
It means similarities between two or more things... Is that what you were looking for?
Answer:
The Earth is constantly changing its position with the sun as the Earth tilts in relation to the sun. This creates the differences in the seasons and the annual warming and cooling cycles of the Earth’s Northern and Southern Hemispheres.
Explanation:
- When the North Pole tilts most toward the sun, the Northern Hemisphere experiences summer.
- Spring and Autumn) occur midway on the Earth’s journey from winter to summer and from summer to winter.
- On March 20 or 21 of each year, the Earth reaches the vernal equinox, which marks the arrival of Spring in the north and Autumn in the south. The autumnal equinox occurs on September 22-23 and marks the arrival of Fall in the north and Spring in the south.
- When it is Summer in the Northern Hemisphere, it is Winter in the Southern Hemisphere, and this has nothing to do with how close or far the Earth gets to or away from the Sun in its orbit. It’s all because the Earth is tilted on its axis.
Answer:
The age of the rock = 2800.6 million years = 2.8 billion years.
A simple method of analysis similar to Carbon dating is used to obtain the required age of the rock. Radioactive substances decay according to first order reaction kinetics. So, plugging all the required parameters into the general equation for amount of substance left in a first order decay gives us the age of the rock.
Explanation:
Half life of Uranium-235 = 700 million years (from literature)
The decay of radioactive substances follow first order reaction kinetics.
The general equation is given as
A(t) = A₀ e⁻ᵏᵗ
A(t) = Amount of radioactive substance left after a particular time = 6.25%
A₀ = initial amount of radioactive substance = 100%
t = time that has passed since the beginning = age of the rock = ?
k = decay constant
The decay constant is related to the half life (T) through the relation,
k = (In 2)/T
k = (0.693/700) = 0.00099 /million years
A(t) = A₀ e⁻ᵏᵗ
6.25 = 100 e⁻ᵏᵗ
0.0625 = e⁻ᵏᵗ
In e⁻ᵏᵗ = In 0.0625 = -2.7726
-kt = - 2.7726
t = (2.7726/0.00099) = 2800.6 million years
t = 2.8 billion years.
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