How many grains of sand are there on earth? That is a good question. But a ball-park estimate is fairly simple.
We will look at fine sand (grain size = 100 microns), and
coarse sand (grain size = 1 mm).
So a cubic mm can hold 1000 grains of fine sand, or 1 grain
of course sand. Obviously grain size is
There are 1x1018 cubic millimeters in a cubic km.
How many cubic km
In my meandering career from academia to government to private sector, and back into all the grey areas in between, I've been an author on a few journal articles, government reports, and other publications. Usually, these are collaborations between groups of separated people, not all of whom interact with every other member of the team. For example, in the academic literature, I have a total of
has launched a recent ad campaign decrying proposed funding cuts to
university research. This ad showcases the products of off-shore corporate giants which are
trying to destroy the Australian high tech industry.
The complicated scientific instrument pictured in the ad from 0:12 to
0:17 is something called a IMS-1280, manufactured by the American technology
Three years ago, I blogged about the cognitive disconnect
between the ecological perceptions of wearing wool and eating beef. However, I did not actually calculate out
exactly what the carbon footprint of a wool sock is. Here it goes:
According to Wikipedia’s wool bale article, a bale contains
about 60 fleeces, and weights 150 ± 50 kg.
This gives a fleece weight of about 2.5 kg.
In the aftermath of the Chelyabinsk fireball last month, there have
been increasing calls to identify asteroids on a collision course with Earth
and develop technologies to deflect them.
This would be a very stupid thing to do.
The reason for this can be seen in figure 1, below. In part A, this figure shows the minimum
deflection necessary to make an asteroid on a collision course with