We know a great deal about the tools left by our ancestors but not much about their culture.
Thirty thousand years ago, did humans look up at the night sky and wonder? I would like to believe they did. We do know that for the past 6,000 years, the moon, planets, and stars have captured our imagination.
It is little wonder we view space as the final frontier for exploration as it has beckoned to us nightly for so long. We have learned much over the past 100 years or so but there is always more to know.
This week, for example, will feature a blue moon. It won't actually be blue in colour, but it will be the second full moon in the month of July.
This interpretation of the term is a relatively recent one, appearing first in the March 1946 issue of Sky & Telescope. The more traditional definition of a blue moon is tied to the difference between the length of a lunar cycle (29.53 days) and the length of the year (365.24 days). There are 12.37 lunar cycle in a calendar year with the result that roughly every three years, there is 13 full moons instead of 12.
Originally, this extra moon was referred to as a blue moon and specifically, the term applied to the third full moon in the season having four full moons. Technically, this would mean that none of the full moons this year are blue moons - which is in keeping with the notion that such events are truly rare.
In any case, a red or orange moon is much more common than a truly blue moon. Typically, on a clear, cloudless night, the moon appears silvery-gray shining by reflected sunlight. However, the light must pass through the atmosphere on its way to you and me.
In doing so, various wavelengths of light may be scattered, with scattering of the blue end of the spectrum much more common.
However, during massive volcanic eruptions, such as Krakatoa in 1883 or Mt. Pinatubo in 1991, large particles of ash - typically one micron in size - can enter the upper atmosphere. These particles are the ideal size for scattering red light and allowing blue light to pass through. The result is an actual blue moon.
But while the moon is the largest of the celestial features, it is perhaps the planets which demand more of our attention. For much of our history, the wanderers have filled a mystical role.
Starting in the 1960s, we began to visit our neighbours. Missions to Venus, Mars, Mercury and the gas giants have told us much about the solar system and the way it was formed. Still, there are many unanswered questions - indeed, this is the hallmark of good science as it usually raises as many questions as it answers.
Pluto sitting on the outer edge of the solar system has always been an alluring target. On the edge of deep space, the surface of the dwarf planet has not succumbed to the turmoil and tectonic upheavals of the inner rocky planets nor is it shrouded in layers of gas. Scientists had high hopes Pluto would reveal a picture of the solar system as it existed 4.5 billion years ago.
The arrival of the New Horizons spacecraft has both confirmed the hopes of astronomers and added to the growing list of unanswered questions.
The preliminary data from Pluto indicates the dwarf planet's surface is covered in the chemicals carbon monoxide and methane, along with nitrogen. At cold enough temperatures these compounds, which are gases in our atmosphere, become solids. Finding them on the surface of Pluto suggests they were common in the early solar system.
This is not really surprising as all three gases have been found throughout the entire galaxy.
However, what has caught NASA scientists by surprise is the composition of Charon, Pluto's largest moon. It appears to be dominated by water and ammonia. Why the two bodies would have different chemical signatures and surface compositions remains unknown.
The answer may be in the data packets New Horizons is still transmitting to Earth. Only five per cent of all of the data has been collected so far.
Pluto also does not appear to have been ravaged by as many impact craters as might be expected. It is closer in appearance to Earth than the Moon.
This is consistent with a view of impact craters on Earth, the Moon, and the inner planets arising from debris dropping into the inner portions of the solar system from the Kuiper's Belt where Pluto resides.
Collisions at the edge of the solar system might be slower and less damaging, but no one really knows for sure yet.
For thousands of years, we have looked into the mysteries of the nighttime sky.
It seems we are still looking.
