During the last week of this month, starting Jan. 23, all five planets visible to the naked eye can be seen at the same time, around dawn each morning. This sight will continue through mid-February. Some sources say that it's starting Jan. 20, but Mercury will be pretty hard to see for the next few days. All throughout this time, the most difficult planet to see will be Mercury, since it will be very close to the horizon. So, to see all five planets, you'll need an open area without a lot of trees or buildings toward the eastern horizon.