NASA’s Dawn spacecraft has finished a long and winding trip, reaching the “dwarf planet” of Vesta this weekend. Vesta is one of the two largest objects we’ve detected in the asteroid belt, at roughly 300 miles in diameter or 1/300 the mass of our moon. Later in the mission, Dawn will visit Ceres, which is roughly four times larger.
The video below includes a good comparison of the pictures we’re receiving now and the best we’d managed to get out of Hubble to date. The Hubble pictures are grainy and blurred, showing little more than a roughly spherical object slowly rotating in the debris field. These new films are very crisp. (Warning: they plugged in some fairly cheesy music over the presentation, but it’s still pretty cool.)
Before we get to the video, though, this story has a strange twist which involves, of all things, climate science. It seems that yet again everything we thought we knew about long term climate change was wrong, and the data involved is so complex that it can be thrown off by something as small and far away as Vesta.
Paleoclimate studies, where scientists look into the past to try and understand changes in Earth’s climate, may be a waste of time if astronomers are correct in their theory that relatively minor bodies like the asteroid Vesta can cause chaotic fluctuations in Earth’s orbit. NASA’s Dawn space-probe flew by Vesta last Saturday…
The new calculations show that Ceres and Vesta gravitationally interact with themselves and with the other planets of the solar system. Because of these interactions, they are continuously pulled or pushed slightly out of their initial orbit. The calculations show that, over time, these effects do not average out. Consequently, their orbits are chaotic, meaning that we cannot predict their positions over long periods.
According to the figures, Ceres and Vesta’s interactions with the Earth cause our planet’s orbit to become unpredictable after only 60 million years. This means that the Earth’s eccentricity, which can cause major climatic variations, cannot be traced back more than 60 million years. This calls into question all Paleoclimate studies that seek to look back further than this point.
BONUS: Scientists explain why Vesta can’t properly be classified as an “asteroid” because it is a differentiated body like a planet, with a core, mantle and crust.