writing in the current issue of Nature report that stars may have an upper limit to their weight. Surveying the Arches cluster--the densest known grouping of stars in the Milky Way--the researchers found no evidence of stars weighing more than 130 solar masses, though in theory the cluster is large enough that stars tipping the scales at up to 1000 solar masses should dwell there. The finding is consistent with observations of a massive cluster in the Large Magellanic Cloud whose heaviest stars weighed in at no more than 150 solar masses.