  Modern sciences and astrophysics in particular study objects and phenomena
not visible in physical terms, that is they cannot be investigated with the
eyes or analogous optical systems. Nevertheless, they make intensive use of
visual representations, showing data in a figurative way, using lights, colors,
and shapes familiar to the user and aesthetically pleasant. Besides being
inaccessible for Blind and Visually Impaired (BVI) users, such figurative
visual representation can lead to misunderstandings about the real nature of
the represented object if the code of representation is not declared. We argue
that multi-sensory representations clearly arbitrary, i.e., that do not aim to
imitate reality, are a valid choice for an effective meaning-making process of
astronomical science for all. In an equity perspective, multi-sensory
representations also create an effective common ground for inclusion among
people with diverse abilities, skills, and learning styles, in the framework of
Universal Design for Learning. In order to investigate our hypothesis we
designed two mono-sensory representation (one only haptic and the other only
acoustic) and tested them in individual and group workshops with both sighted
and BVI users. We then used our results to guide the design of a multi-sensory
representation of non-visible astronomical data including visual, acoustic, and
haptic stimuli. We tested this representation as well, in order to refine and
propose it to the public. The result is the exhibit Sense the Universe, to be
used for outreach and education. Sense the Universe was part of a museum
exhibition attended both by sighted and BVI users. Our findings suggest the
validity of multi-sensory representations for a truly and effective engagement
in scientific learning, both in terms of intelligibility and persistence of
scientific contents and of a more equal access to scientific culture.
