If you look at the sky only in terms of “stars”, you’re already missing a lot of interesting stuff.
That was the first thing that the resident astrophysicist said to our impromptu social group. We were having drinks on an outdoor platform that straddled part of Howard Hughes’ old “Mission Control” building and the conversation had come to a lull. Someone piped in with “So, tell us something about these stars…” while waving toward the heavens – on the night of a “super moon”. The sky was so clear and bright that the sky still had a blue cast to it and the street lights that dotted the neighborhood seemed superfluous. His initial response yielded some half-knowing chuckles, mine included. As the banter meandered through “that’s not a star, that’s a planet” to another part of the sky where he clarified “that’s not a planet, that’s a galaxy” he then digressed into how all astrophysics students fall in and out of love with the moon. It happened that the night of a “super moon” is a particularly good case study in why that’s true. At first, students spend time observing the moon in all its glory. Then, in later years when students move on to other heavenly bodies, the moon (particularly when full) is at worst an obstruction – or at a minimum, a source of light pollution that makes the observation of distant bodies much more difficult.
It seems that this isn’t only the problem of astrophysics students. A new paper out of Cornell University details the latest observation and what it could mean for cosmology. This Slate article offers an explanation in layman’s terms (which is where I wrapped my head around the latest news). What’s interesting to me is that they haven’t revised their evaluation of mass contained in the universe, but the observation does change how they appraise the distribution of that mass in the early stages of universal expansion. This may seem like a shell game, but it has implications on how both observational and theoretical physicists pursue their field. What has always blown my mind is that when we’re looking at distant bodies we’re also looking back in time. At that scale, we’re not only looking farther out but also further back. So I’ll be interested in how this changes how scientists extrapolate from that data, and what conclusions can be drawn from the consequences of this new information. One thing I do know about “big number” equations like those that explain cosmology – little changes can have a big impact on the final result. While no one says that this will cause an immediate shift in the way the universe is seen, I’m interested in the ripple effect on cosmological theories that are brought forward (and conversely, which ones are sent into the dustbin of history).
And so I’m reminded of that long, bright night with too few stars in the sky and too many rounds of drinks among friends. All of the amateur star-gazers tested the patience (if not the knowledge) of our resident expert. Eventually, he became a bit exasperated and told the group how we weren’t really asking the interesting questions. So we took the bait, and he laid a series of facts that left everyone close to speechless. He told us about how the Milky Way is “eating” another dwarf galaxy, and that our solar system is near one of the intersections where the stars are streaming from that galaxy to ours. He also let everyone know that we’re currently moving up in the galactic disk at about 7 miles per second. But instead of flying off into space, the Milky Way is 1000 light years thick at our current location, and we will eventually start moving “down” as the mass of the other stars pull us back toward the center of the disc. Then he moved closer to home and described how the moon was moving out of Earth’s orbit by 3+ centimeters per year, but that it would never escape Earth’s gravity due to tidal lock and conservation of momentum. His finishing statement was how that life on Earth would never have to deal with our Sun going nova because we’d either figure out how to move off of the planet or would be killed off by a major extinction event – like a rock the size of Manhattan streaming out of the Kuiper Belt and hitting the planet. In that case, the friction would be so high that the atmosphere and ocean under the impact site would literally vaporize and be ejected into space before the object struck the Earth.
So, the moral of the story is that no matter what you think you know, it always pays to check your assumptions. And as far as that night was concerned – I learned to never go out drinking with an astrophysicist. Even when sober my mind is not prepared for that kind of exercise in scale.