Longstanding knowledge of a few major artists and artworks may be altered. The Vatican believes it has uncovered a 'new' Caravaggio; French experts have scientifically analyzed da Vinci's painting style; and Thomas Eakins' iconic "The Gross Clinic," perhaps the most important American painting of the 19th century, has been restored to reveal another artist's hand reworked the final masterpiece.

Italy celebrated the 400th anniversary of Baroque master Caravaggio's death over the weekend. Galleries and churches holding his work stayed open all night. The BBC reports that the Vatican newspaper headlined a possible new discovery: A previously unknown Caravaggio painting depicting the martyrdom of St Lawrence is owned by the Jesuits in Rome.

Some experts have their doubts over the attribution. For one, Caravaggio is not recorded to have depicted St. Lawrence. The Vatican maintains that the painting's style is consistent with his hand.

French researchers announced Friday that they have scientifically analyzed Leonardo da Vinci's style for the first time with precise results. Non-invasive x-ray fluorescence was used to measure his "sfumato" technique.

The team says seven paintings by the Renaissance master in the Louvre, including the Mona Lisa, reveal da Vinci painted up to 30 ultra-thin layers to achieve his signature shading.

After a ten-month restoration, Thomas Eakins' The Gross Clinic has re-emerged with shocking results. The extremely bright portions of the painting, and other elements, are an overpainting executed by another artist between 1917 and 1925.

“This is the picture that’s been in a thousand textbooks,” Kathleen A. Foster, senior curator of American art at the Philadelphia Museum of Art, told The New York Times. “It’s the painting everyone knows. Unfortunately it’s not the one Eakins painted.”

Eakins had intended a much darker chiaroscuro for his jarring, ambitious, and celebrated painting of 1875 which depicts a surgeon at work with a gallery of medical students watching.

The Pennsylvania Academy of the Fine Arts and the Philadelphia Museum of Art raised $68 million in 2007 and 2008 to keep "The Gross Clinic" in Philadelphia when its previous institutional owner announced plans to sell it.

The painting is on view July 24 through Jan. 9 in “An Eakins Masterpiece Restored: Seeing ‘The Gross Clinic’ Anew,” at the Philadelphia Museum.