Glossary term: Accelerating Universe
Description: In the late 1990s, measurements of the light emitted from Type Ia supernovae (a class of exploding star), located in very distant galaxies showed that they appeared fainter than expected for a universe with a constant rate (speed) of expansion. The measurements were consistent with the scenario for a universe where the rate of expansion was accelerating. The cause for the accelerated expansion is attributed to dark energy, the nature of which is still unknown and a topic of current research. The accelerated expansion is occurring on very large scales and has no significant effect in individual gravitationally bound galaxies.
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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher
The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".
