Our human's eyes can only see within visible wavelengths. When we look into the sky with telescope, if there are stars or galaxies that emitting non-visible light, how could we see them? When astronomers estimate the number of stars and galaxies in the universe, do they consider those invisible ones?
What is your basis for assuming an entire galaxy emits only in the infrared? Even allowing for large cosmological redshifts? Have you checked available deep space surveys before posting this 'inquiring' thread?
Radio astronomy https://en.wikipedia.org/wiki/Radio_astronomy Gamma-ray astronomy https://en.wikipedia.org/wiki/Gamma-ray_astronomy X-ray astronomy https://en.wikipedia.org/wiki/X-ray_astronomy Infrared astronomy https://en.wikipedia.org/wiki/Infrared_astronomy Radar astronomy (local) https://en.wikipedia.org/wiki/Radar_astronomy Dark matter detection https://www.udel.edu/udaily/2021/may/dark-matter-detection-tabletop-sensors-astronomy-physics/ Rogue planet: "A rogue planet is a planetary-mass object that does not orbit a star." New telescope will detect 'rogue' planets that could outnumber stars https://www.msn.com/en-us/news/tech...lanets-that-could-outnumber-stars/ar-BB18r7fy "The Roman Space Telescope's secret weapon in finding these nomad planets is a technique called gravitational microlensing. It uses the gravitational pull from stars and planets to warp light coming from stars that pass behind them. When the light is magnified, scientists are able to see previously hidden objects, including rogue planets. Microlensing has been in use for some time but the Roman will be a 'game changer' for astronomers."
