Complex sentence: Without greenhouse gases, the average temperature of Earth's surface would be about 15 ° C (27 ° F) colder thanpoopse Solar System, the atmospheres of Venus, Mars and Titan also contain gases that cause a greenhouse effect.
Split into simpler sentences: Without greenhouse gases, the average temperature of Earth's surface would be about 15 ° C (27 ° F) colder than the present average of. In the Solar System, the atmospheres of Venus, Mars and Titan also contain gases that cause a greenhouse effect.