The Universe Is Made Of.... Umm.... Well...

Often when I'm teaching an astronomy class to the general public, I begin with a “what is the universe made of?” slide. I show pretty pictures of stars, galaxies, planets, etc. and discuss all the different objects astronomers are studying in outer space. But when I do this, I'm technically lying to everyone. These observable objects actually make up only 4% of the entire universe! To be honest, astronomers have almost no idea what makes up the other 96% of our universe! The current most popular idea is that the universe is also made of 22% dark matter and 74% dark energy. Dark matter is just “stuff” distributed throughout space that interacts gravitationally with other things, but doesn't emit or interact with light. Ergo “dark” matter. Dark energy is this mysterious entity that is causing the expansion of our universe. The universe is expanding at an increasing rate, and therefore something must be “pushing” the universe, giving it energy to increase its rate of expansion. Nobody really understands what this energy is or where it comes from, but we call it “dark” energy because it must be there, we just can't see it. A bit unnerving that the people that are supposed to know everything about outer space really have no clue about 96% of it huh? So how do we “know” that this crazy dark matter and dark energy exists? Well that's a topic for upcoming ADYK posts....

image credit: Hubble/NASA

An Insight Into Haumea

Image from the Keck telescope of Haumea and its moons Hi'iaka (top) and Namaka (bottom)

An insight into Haumea… literally! As you may recall, I introduced you to my egg shaped friend back in April. If you've forgotten, it's an egg shapes dwarf planet beyond the orbit of Neptune that has crystalline water ice on its surface.  Astronomers expect the solar radiation from the sun to destroy the crystalline structure of any surface ice, so for Haumea and it's moon to show this structure, something funny must be going on. An answer to this question comes from Dr. C. Dumas and collaborators from the European Southern Observatory. They believe that a mixture of tidal heating and radiogenic heating provides enough energy to essentially counteract the solar radiation and keep the surface water in crystalline form. Tidal heating is when another body (Haumea's moons) tug on the parent body (Haumea). This constant squeezing motion produces energy and keeps the planet warm. Haumea's moons are not large enough to create a lot of tidal heating, so astronomers think that radioactivity in its core produces the rest of the energy! Haumea is basically a giant nuclear power plant with radioactive Uranium and Thorium in its core producing tons of energy! It will take some time and technology to determine if these theories are correct, but they seem like the only logical option. Unless, of course, there is something new and exciting happening in Haumea that astronomers haven't thought of yet!