It's a well known law of research science, known as the "Professor Astronomy Law," that the last person to discover something new gets the credit. Today has seen two examples of that.
The first is from today's 365 Days of Astronomy podcast, which features the story of Thomas Harriot. Harriot was a British gentleman who lived in the early 1600s. New research works has shown that Harriot likely was the first person to make maps of the moon through a telescope, beating Galileo by at least a few months. Harriot didn't make a big deal out of his findings (the podcaster, Oxford historian of astronomy Allan Chapman, speculates that Harriot was well off and didn't want to get into any trouble), so Galileo gets the credit. And, most likely, other people also looked at the moon through the spyglasses around the same time as Galileo. But since Galileo was the most successful at publicizing his findings, he gets the credit.
The other story is much more modern. I was surprised to see a press release today claiming that astronomers have made the first ever ground-based detection of the atmosphere of an exoplanet (a planet around another star). It surprised me because Seth Redfield, one of my colleagues and friends, announced such a finding 13 months ago.
I don't know the astronomers involved in the more recent discovery, but they are quoted as saying "Others have tried to detect planetary atmospheres from Earth, but to no avail." Perhaps they were misquoted. Perhaps they weren't aware of Seth's work. Perhaps they don't believe his detection. It's hard to get scientific details from the press release, but I suspect that what this team (along with a Dutch team also mentioned in the same article) has done is to view the planet's atmosphere in infrared light, whereas Seth's team detected it in optical light. There is a lot more atmospheric work that can be done in the infrared than in the optical (molecules like carbon dioxide and water are common in the infrared), so this is an important find. But it's not the first detection of an exoplanet atmosphere from the ground.
This is a problem with press releases; sometimes the science gets garbled, sometimes claims are made that are not quite right. That's why we astronomers (and most scientists) prefer to use papers published in our official professional journals to findings announced in press releases. The journal articles are longer, more complete, and more technical. I haven't seen the paper on the new exoplanet find yet, but it should be out very soon, and I'll let you know what I find.
Update: As I kind of suspected, there was some subtle nuance to the wording of the press release that was lost in the Space.com article. Universe Today's article on the discovery gives the all-important nuanced wording: "For the first time, astronomers have measured light emitted from extrasolar planets around sun-like stars using ground-based telescopes." (emphasis mine). The two studies found infrared light emitted from the hot atmosphere of the planet, whereas Redfield's team measured light from the star absorbed by the planet. It's an important distinction, but in both Redfield's case and the newly-announced data, the teams are detecting the atmosphere of the planet.