Deep space — meaning the vast, mostly empty regions far from stars, planets, and galaxies — has a background temperature of about 2.725 kelvin (K), which is roughly –270.425 °C or –454.765 °F.
On Mars at night, temperatures can drop to around –73 °C (about –100 °F) in many regions.
Night (lunar night, lasting ~14 Earth days): about –173 °C (–280 °F)