Here's why:

* Gas giants: The vast majority of discovered exoplanets are gas giants like Jupiter and Saturn, vastly different in composition and environment from Earth.

* Hot Jupiters: A significant portion of these gas giants are "hot Jupiters," orbiting extremely close to their stars, making them incredibly hot and unsuitable for life as we know it.

* Super-Earths and mini-Neptunes: While some exoplanets are rocky, many are "super-Earths" or "mini-Neptunes," with sizes and masses larger than Earth but smaller than Neptune. These planets often have thick atmospheres and potentially very different surface conditions.

While the search for Earth-like planets is ongoing, we've yet to find many that closely resemble our home.