Self-study
When astronomers observed the comet Schwassman-Wachmann 3 becoming 1,000 times brighter in September 1995, they correctly hypothesized that its increased brightness was a result of the comet's breaking up—when comets break up, they emit large amounts of gas and dust, becoming visibly brighter as a result. ████████ █████ ████████████ ███ ███ ██████ █████ ███████████████████ █ ████████ ████████ ████ ██████ █████ ████████ █████ ████ ██████ ██████████ ████ ███████ ██ ██ ██████████ ███ ██████ ███████
"Surprising" Phenomenon
When a comet breaks apart, it emits dust and gas that makes it appear brighter. So why did scientists observe a certain comet increase in brightness months before they observed it breaking apart?
Objective
The correct answer will explain why the comet’s visible increase in brightness preceded its fragmentation. Given that the release of gas and dust is what gives broken comets their brightness, one possibility is that the comet released gas and dust before it visibly split apart.
13.
Which one of the following, ██ █████ ████ █████ ██ ███████ ███ ████████ ████████ ██ ███ ██████████ ██████
a
Comets often do ███ ████ ███ ███ ████ █████ ███████ █████ █████ ████ ████ █████ ██ █████ ███
If comets release gas and dust only after breaking up, then we’d expect to see the breakup first, making the discrepancy even harder to resolve. The right answer must explain why the brightness increase was observed before the breakup.
b
The reason comets ██████ ████████ ████ ████ █████ ██ ██ ████ ███ ███ ███ ████ ████ ████ ████ ███████ ██████
This explains why comets appear brighter when they break, but the right answer must explain why the brightening was observed before the breakup in this case. This doesn't help us with that timing.
c
Gas and dust ███ ██ ████████ ██ ██████ ██ █ █████ ████ ██ ███ █████ ██ ███ ██████ ███ ███ ███ ████████
If gas and dust can be released before the comet fully breaks apart, then scientists could observe the comet brightening before they observed its fragmentation. This resolves the conflict.
d
The amount of ███ ███ ████ ███████ ████████ █████████ ██████ ███ ██████ ████ █████████ ███████ █████████
This is redundant. We already know that the comet got visibly brighter before it was observed breaking up in November. The right answer must explain why the brightening was observed so early.
e
The comet passed █████ ██ ███ ███ ██████ ████ ██████ ███ ███ █████████████ ██████ ██████ ██ ██ █████ ███
This explains why the comet broke apart, but the right answer must explain why scientists observed it brightening before it broke up. This doesn't tell us anything new about the brightening.