decorative picture of space events




Fermi's Piano Tuner Problem

How Old is Old?

If the Terrestrial Poles were to Melt...

Sunlight Exerts Pressure

Falling Eastward

What if an Asteroid Hit the Earth

Using a Jeep to Estimate the Energy in Gasoline

How do Police Radars really work?

How "Fast" is the Speed of Light?

How Long is a Light Year?

How Big is a Trillion?

"Seeing" the Earth, Moon, and Sun to Scale

Of Stars and Drops of Water


A Number Trick

Designing a High Altitude Balloon


Calendar Calculations

Telling Time by the Stars - Sidereal Time

Fields, an Heuristic Approach

The Irrationality of

The Irrationality of

The Number (i)i

Estimating the Temperature of a Flat Plate in Low Earth Orbit


The Transcendentality of


Maxwell's Equations: The Vector and Scalar Potentials

A Possible Scalar Term Describing Energy Density in the Gravitational Field

A Proposed Relativistic, Thermodynamic Four-Vector

Motivational Argument for the Expression-eix=cosx+isinx

Another Motivational Argument for the Expression-eix=cosx+isinx
Calculating the Energy from Sunlight over a 12 hour period
Calculating the Energy from Sunlight over actual full day
Perfect Numbers-A Case Study
Gravitation Inside a Uniform Hollow Sphere
Further note on Gravitation Inside a Uniform Hollow Sphere
Pythagorean Triples
Black Holes and Point Set Topology
Additional Notes on Black Holes and Point Set Topology
Field Equations and Equations of Motion (General Relativity)
The observer in modern physics
On Expansion of the Universe - PDF File

What if an Asteroid Hit the Earth?

Suppose a cylindrical asteroid 10 km in height x 10 km in diameter impacted the earth at 30,000 mph. Calculate the energy dissipated, in megatons of TNT, and the rate at which it is dissipated, in watts.

Let the density of the asteroid, rho, be five times the density of water, i.e.,

rho = 5000 kg/m3.

Then, the mass of the asteroid is

(5000 kg/m3) x pi (5000 m)2 x (10,000 m) = 4 x 1015 kg

and the kinetic energy, traveling at 30,000 mph (= 1 x 104 m/sec) is

(1/2) x (4 x 1015 kg) x (1 x 104 m/sec)2 = 2 x 1023 joule.

Now, one megaton of TNT delivers 4.2 x 1015 joule, so that the required energy in megatons of TNT is

5 x 107 megatons

or 50 million megatons! The time for the asteroid to impact the earth is

(10,000 m)/(1 x 104 m/sec) = 1 sec

so that the rate of energy dissipation in watts is

2 x 1023 watts,

or 200 billion trillion watts!!!

Such an object might have been responsible for causing the extinction of the dinosaurs at the end of the Cretaceous period. A layer of Iridium has been found in the Cretaceous-Tertiary (K-T) boundary, which appears to be world encircling (Alvarez, et. al.). Such a layer might have been deposited after an asteroid impact of great magnitude. In fact, the remains of a 65 million year old impact site have recently been found, providing an excellent candidate for the K-T event. From various geological survey data (originally intended to locate promising sites for oil drilling), the site is in the Yucatan.

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Responsible NASA Official: Theresa.M.Scott (Acting)