Viewing posts by christian
What N Things?
Posted by: christian on 29 Aug 2019
The mildly controversial geocoding system What3words encodes the geographic coordinates of a location (to a resolution of 3 m) on the Earth's surface into three dictionary words, through some proprietary algorithm. The idea is that human's find it easier to remember and communicate these words than the sequence of digits that makes up the corresponding latitude and longitude. For example, the Victoria Memorial in front of Buckingham Palace in London is located at (51.50187, -0.14063) in decimal latitude, longitude coordinates, but simply using.woods.laws in the language of What3words.
Visualizing the Earth's dipolar magnetic field
Posted by: christian in Featured on frontpage on 28 Aug 2019
The magnetic field due to a magnetic dipole moment, $\boldsymbol{m}$ at a point $\boldsymbol{r}$ relative to it may be written $$ \boldsymbol{B}(\boldsymbol{r}) = \frac{\mu_0}{4\pi r^3}[3\boldsymbol{\hat{r}(\boldsymbol{\hat{r}} \cdot \boldsymbol{m}) - \boldsymbol{m}}], $$ where $\mu_0$ is the vacuum permeability. In geomagnetism, it is usual to write the radial and angular components of $\boldsymbol{B}$ as: $$ \begin{align*} B_r & = -2B_0\left(\frac{R_\mathrm{E}}{r}\right)^3\cos\theta, \\ B_\theta & = -B_0\left(\frac{R_\mathrm{E}}{r}\right)^3\sin\theta, \\ B_\phi &= 0, \end{align*} $$ where $\theta$ is polar (colatitude) angle (relative to the magnetic North pole), $\phi$ is the azimuthal angle (longitude), and $R_\mathrm{E}$ is the Earth's radius, about 6370 km. See below for a derivation of these formulae.
Some analysis of the demographics of India
Posted by: christian on 2 Aug 2019
This Jupyter Notebook can be downloaded and viewed at my GitHub repository.
Impact craters on Earth
Posted by: christian in Featured on frontpage on 28 Jul 2019
The Earth Impact Database is a collection of images, publications and abstracts that provides information about confirmed impact structures for the scientific community. It is hosted at the Planetary and Space Science Centre (PASSC) of the University of New Brunswick.
The Star Wars opening crawl in Matplotlib
Posted by: christian on 21 Jul 2019
Matplotlib isn't the obvious choice for depicting the Star Wars opening crawl, but that isn't a reason not to try: