Take this new space photo, for example. It shows a cloud of dust and gas (shown in red) next to a bright star. However, the star is actually much closer to the Earth than the cloud is. Stars like this, which lie between the Earth and the object that an astronomer is trying to observe, are called ‘foreground stars’. They are much brighter than the other stars in photos because they are closer to us.
Credit:
ESO/APEX (MPIfR/ESO/OSO)/A. Hacar et al./Digitized Sky Survey 2. Acknowledgment: Davide De Martin