The traditional New Year's Eve drink made from champagne and orange juice is called a mimosa.
A mimosa combines sparkling wine, traditionally champagne, with orange juice. It is commonly served in a flute or wine glass and is strongly associated with brunch, weddings, and celebratory occasions, including New Year's Eve. The drink's bright color and simple two-ingredient recipe helped it become a familiar party cocktail.
The cocktail is often traced to the Ritz Hotel in Paris, where it was reportedly created in 1925. Its name comes from the yellow-flowering mimosa plant, whose color resembles the drink. Recipes vary in the ratio of sparkling wine to juice, so the exact strength is not fixed.
A mimosa is sometimes confused with Buck's Fizz. The names are closely related, but Buck's Fizz is generally described as containing more sparkling wine and less orange juice. Champagne is also a specific sparkling wine from France's Champagne region, while many mimosas use other sparkling wines.