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naked-eye
something visible or accomplished without the aid of binoculars or a telescope (e.g. a naked-eye object or naked-eye observing)
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near-infrared
light from the part of the infrared band of the electromagnetic spectrum closest to the visible range
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nebula
a cloud of interstellar gas and dust; some nebulae represent stellar nurseries, others represent stellar graveyards
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neutrino
a subatomic particle produced in nuclear reactions and in supernovae that very rarely interacts with matter; neutrinos have no electrical charge and travel at or very close to the speed of light
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neutron
a subatomic particle with no electric charge that resides in an atomic nucleus; it has about the same mass as a proton
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neutron star
the collapsed, extraordinarily dense, city-sized remnant of a high-mass star
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new moon
the phase in which the moon is in the same direction as the sun in Earth’s sky, so it is unilluminated and invisible
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nova
an explosion on the surface of a white dwarf that is accreting matter from a companion star, which causes the system to temporarily brighten by a factor of several hundred to several thousand
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nuclear fusion
the process by which two atomic nuclei combine to form a heavier atomic nucleus; this is the energy source that causes most stars to shine
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nucleosynthesis
the creation of heavy elements from lighter ones by nuclear fusion
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nucleus
the central region of an atom, comet, or galaxy
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