Molecular Clouds

Molecular clouds are regions of gas and dust from which stars and planets form. They are generally colder regions, so are darker than the surrounding areas. They can only be seen when they are in front of a brighter region and appear as "holes" in space.

A good example of a molecular cloud is the Horsehead Nebula in Orion.

Credit and Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight, CFHT

These clouds are also called dark nebula because they don't emit radiation in the visible spectrum. These are the regions of space where stars and planets form. The cloud will start to collapse because of an outside force, like the wavefront of a supernova. The collapse will also create rotation on the cloud. From the conservation of angular momentum, as the cloud collapses, the rotation also speeds up. At the core of the cloud, the density increases and the temperature increases. This is where the protostar is formed. The outer sections of the cloud are where planets, dwarf planets, asteroids, comets, and other bodies in a planetary system will form.

The Satellite of Makemake

Makemake is a dwarf planet in the outer edges of the solar system in the Kuiper Belt. It was discovered in March 2005, and announced by Mike Brown in July of 2005. It is about 2/3 the size of Pluto, so it is relatively small. However, it was recently discovered that Makemake has a companion body discovered in April of 2016 (from images taken in April of 2015 from the Hubble Space Telescope). It is not the only dwarf planet with a satellite.

Pluto has five, including Charon. Eris, the largest dwarf planet by mass (Pluto is larger by volume), has one (Dysnomia). Haumea has two. Satellites around dwarf planets may be pretty common.

April

April is the fourth month of both the Julian and Gregorian calendar. It was once the second month of the old Roman calendar until the Numa calendar was created in 700s BCE. Where does the name April come from?


There are many ideas. One is that is named for the Roman word aperire which means to open, as this it the first full month of spring and flowers begin to open. It could also be related the Greek goddess Aphrodite whose Roman equivalent Venus held the month sacred.


The zodiac constellations (according the pseudo-science astrology) are Aries (the ram) and Taurus (the bull). In actuality, the Sun is in the constellation Aries right now, but was in Pisces (the fish) up until April 19. The Sun won't be in Taurus until mid May. The original astrological signs were based on the Sun's position 2000 years ago and was covered on my post about the precession of the equinoxes. You can also revisit my post about the Zodiac, as well.


Next month, we'll talk about May...and a lot sooner than near the end of the month.