I enjoy traveling, whether taking a trip to visit relatives for Christmas or a summertime vacation to witness the beauty of creation. However, any trip with my family (wife and five kids) requires lots of preparation in order to achieve success. Clothes must be packed, bills paid, lodging reserved, and the list goes on. These tasks must also be accomplished in the proper order. Trying to pack clothes after a trip begins is highly unadvisable. Likewise, when the solar system formed, certain events needed to take place before others in order to establish a life-friendly cosmic habitat.
As described in Rare Earth, advanced life depends on plate tectonics. In order for a planet as small as Earth to experience long-standing plate tectonics, it must have a large supply of radioactive nuclei that will emit the heat that drives tectonic activity. These nuclei form in the massive supernova explosions that occur as stars die. However, like packing for a trip, the nearby supernovae that seed the planets with radioactive material must take place at the proper time. If they occur too early (or too close) the supernovae might blow the solar nebula apart and prevent the formation of the solar system. If they occur too late, the planets will have already formed without incorporating the necessary radioactive elements. I have detailed some of the evidence about this fine-tuning in a previous TNRTB.
Astronomers and geophysicists have discovered evidence of such “fine-timing” by looking at meteorites that formed in the early solar system and recently landed on Earth. Some of these meteorites, known as chondrites, record the conditions present in the early solar system because they have not been melted or otherwise processed since their formation. They include different components such as calcium-aluminum inclusions (CAIs) and chondrules. According to most models that incorporate finely timed supernova explosions in the early solar system, these components form at different times. In particular, the chondrules should form later than the CAIs.
The research measured ages of the chondrules at 1.66 million years younger than the CAIs. This number supports models where the aluminum enters the solar nebula shortly after a nearby supernova explosion occurs. It also provides further evidence that the solar system formed between 4.57 and 4.56 billion years ago. The proper timing of events in the early solar system ensured that Earth had all the necessary “clothes” so that the life-essential plate tectonics would continue for the duration of Earth’s trip through this universe.