Physicists introduced the concept of dark matter after they determined that, among other things, galaxies didn’t have enough mass to explain their rotation. Dark energy with its strange properties is needed to explain, for example, the evolution of the universe during its early childhood when it must have experienced a sudden, tremendous growth spurt. Both concepts are incorporated into the current model of the universe called Lambda-CDM. This model, however, has a small disadvantage: it says nothing about what dark matter and dark energy are made from. Experimental physicists haven’t gotten any closer to an answer to this question…

This past year, our Solar System had an interstellar visitor. ʻOumuamua, which was discovered in October 2017, was first thought to be an asteroid. Then it was determined that it had changed its course by itself (and not due to gravitational interaction with the Sun or the planets). Its “propulsion system” is thought to be volatile substances that sublimated during the object’s approach to the Sun – typical behavior for a comet. But where did this extrasolar comet come from? (more…)

The closest individual star to the Sun is apparently orbited by a rocky planet. This was discovered by astronomers using the radial velocity method. This method is based on the fact that stars and planets affect each other. With each revolution of a planet around its host star, the star will also move a little, toward and away from the Earth. This produces a red-shift or blue-shift in the star’s light and this shift can be measured. However, the effect is very small, so very precise observations are needed over a very long time period. In the case of…