Is The Celestus legal in Standard, Modern, and Commander?

The Celestus is legal in: Modern, Pioneer, Legacy, Vintage, Commander, Historic.

What type of card is The Celestus?

The Celestus is a Legendary Artifact. Its oracle text reads: "If it's neither day nor night, it becomes day as The Celestus enters. {T}: Add one mana of any color. {3}, {T}: If it's night, it becomes day. Otherwise, it becomes night. Activate only as a sorcery. Whenever day becomes night or night becomes day, you gain 1 life. You may draw a card. If you do, discard a card."