Highly-excited atoms, often known as Rydberg atoms, display high sensitivity to external electromagnetic (EM) fields. In addition to their use in quantum computing, Rydberg atoms can be configured for sensing applications. Such sensors make use of non-destructive read-out of Rydberg states, which is implemented optically, including fluorescence detection of low-lying Rydberg states. A range of different Rydberg sensing modalities have been developed; these include those developed for microwave standards and imaging in the Terahertz regime to sensitive digital communications techniques in radio and microwave bands. For Earth observation, a sensor that detects specific channels of incoherent radiation is needed – a Rydberg Receiver (RR). In this presentation, I will compare RRs to classical radiometers. As RRs are based on the response of an atom to an oscillating electric field, they are conceptually different from a classical antenna. Thus, concepts such as effective apertures must be translated to equivalents of a new modality that uses the language of electric fields rather than RF power.  In addition, one must convert between scene or antenna temperatures to electric field sensitivities. This conversion draws out a natural comparison to low-noise amplifiers (LNAs). A Rydberg atom could be considered an LNA with a highly tunable ‘carrier frequency’ sensitivity range but low instantaneous bandwidth. I will discuss current sensitivities/noise temperatures compared to non-cryogenic, off-the-shelf LNAs and conclude by identifying the most promising operation frequencies of RRs, discussing the necessary developmental steps, and likely implications of relevant noise sources.