Why should a galaxy have bluish spiral arms dotted with red patches and dark lanes. Why should it have a central region that is yellow and spherical rather than flat? Why are they flat to begin with? Because Galaxies are so huge, and made from hundreds of Billions of stars that change over the course of their lives, a galaxy shows the entire life cycle of a star in its own structure. Stars are born along spiral arms, where most of the thick dust and gas clouds are concentrated. The dark dust lanes of spiral arms condense to form stars,...
I’ve seen images from the Sun in all different wavelengths of light. It looks very different across the electromagnetic spectrum, with some wavelengths making up more of the Sun’s total energy output than others. What’s always striking to me is seeing the images of the Sun that show its structure, including the strange and beautiful features of plasma that dance across it’s surface. A recent APOD captures just such a concept. This image shows the Sun in Hydrogen Alpha, a wavelength of light at 656 nanometres. This is from the ionization of Hydrogen, where the electron is excited and transitions...
Categorizing objects in the universe can be difficult. The fiasco with Pluto over the last decade is more than proof of that. We generally look to location and then to size as the two main methods for classifying the stuff that permeates the cosmos. Galaxies contain stars, which host orbiting planets, which host orbiting moons; While asteroids fly in between planets and icy comets are wander through the outskirts of star systems. But what about the in-between objects? Often we find strange things in strange places. There are moons in our solar system that are larger than planets. What would...
