No one—not even an astrophysicist—works in a void. All research takes place in the context of what we currently believe to be true, and this context can either lend credibility to a claim or erode it. The newer and stranger the result, the greater the burden of proof.
How does this claim compare to other studies on the same subject? Is there consensus in the field? Who disagrees, and why?
Scientists form a community, and as in all communities, not everyone is in perfect agreement. Even so, if there’s one thing all scientists agree on it’s reproducibility. For one person’s research to be believable, other people using the same tools or techniques must be able to produce the same result.
Has anyone else in the field verified the result? If a researcher is using a new tool or technique, are there other tools or techniques that can verify the result? Searching the Web for other articles on the same topic is an easy way to find a second opinion—and often a third and fourth, to boot.