The Adler Planetarium turned 75 a few years ago. And at that point, set a long-range goal: to completely redo the theater with a new dome, new sound system and new projector.
In addition to seeking funds from private donors, the planetarium turned to city, state and federal politicians to raise money.
"He voted for nearly a billion dollars, including by the way $3 million for an overhead projector," McCain said.
McCain brought up the earmark again Wednesday on the campaign trail in Pennsylvania also saying that Obama benefitted from fundraisers associated with the planetarium.
"Purely coincidentally the chairman of that planetarium pledged to raise more than $200,000 for Senator Obama's campaign," said McCain.
In response, the planetarium's president explained what the money would pay for.
"The students come here on a field trip to actually experience for themselves a dark night sky, which they can't see from the city of Chicago," said Dr. Paul Knappenberger, Adler Planetarium.
The planetarium's projector is this machine, the zeiss mark-6. It was state of the art when it was first installed in 1970.. But it's showing wear and tear, and is no longer supported by parts or service from the manufacturer. The planetarium says it's a resource for thousands of Chicago-area school children who visit it each year.
The planetarium has been lobbying for a few years for money to fund a multi-million dollar overhaul of its sky theater. Last year, it approached a bipartisan Illinois congressional delegation, which included Obama.
"Senator Obama and others did put that earmark request in. It did not get funded," said Knappenberger.
In response to McCain's comments, Obama said in a statement that he is, "Firmly committed to enhancing our nation's science education programming before leveling dubious charges against this science programming again, John McCain should check his own record - he voted for $200,000 in funding for the Adler Planetarium."