What would it be like if we had two suns?

Answer 1

The universe would be largely unaffected if Venus became a star, but the solar system would be profoundly affected. Stars must have a minimum size and mass to form and begin nuclear fusion. If Venus was replaced with a minimum-sized star, it would have a profound effect on the planets of the inner solar system. They'd get toasted over the course of a short time and be reduced to bruned out cinders. Certainly the mass required for stellar formation could, if conditions were right, "suck in" the inner planets of the solar system and consume them within the star. It is probable that another star so close to the sun (and they do exist with high frequency in the galaxy - they're called double stars) could "clear out" the inner solar system of any orbiting body or debris. The massive gravity of a star would probably not permit any small bodies to orit closely and survive. Lastly, the orbit if Venus is close to the sun. The double star system could set up mutual gravitational attraction, and it is possible that one of the two stars could begin to "siphon off" mass from the other and eventually destroy or extinguish it.

Answer 2

It's unlikely we would be here at all. Two Suns would orbit each other at the centre of the two masses - a bit like on a see saw with the centre of mass being the fulcrum. Considering two stars of about equal mass.

As the two "Sun" orbit each other, the gravitation pulls would be so destabilising, that it is unlikely any planet could form within the two Suns.

It is possible that a planet could form outside of the orbits of the Suns, but the differences in gravitation and heat would make it unlikely for life to evolve.

However, if one Sun was massive and the other minor and had an orbit many millions of miles away, then an Earth could form around the "major" star as if the other didn't exist.