Green Star

"AY-O! Did ya see that? Those Prankster Comets were green! That means there are Green Stars around now! Those must be the cosmic jewels I keep hearing about! Those Green Stars are pretty hard to find, so keep your eyes and ears peeled! Take it away, Captain!"

- Lubba

Green Stars (referred as cosmic jewels by the Green Lumas in Super Mario Galaxy 2) are collectible green-colored Power Stars that debut in Super Mario Galaxy.

Super Mario Galaxy
In Super Mario Galaxy, there are only three Green Stars, each of which is hidden away in a different galaxy. Collecting all three of them grants Mario access to the three Trial Galaxies on the Planet of Trials: the Rolling Gizmo Galaxy, the Loopdeeswoop Galaxy, and the Bubble Blast Galaxy.

Locations

 * Battlerock Galaxy - Luigi under the Saucer: Rescuing Luigi from a cage in the first level.
 * Buoy Base Galaxy - The Secret of Buoy Base: Through a Pipe under the Buoy Base sealed in a cage which needs to be broken with a Torpedo Ted.
 * Dusty Dune Galaxy - Treasure of the Pyramid: Collecting five Silver Stars in the Pyramid Planet.

Super Mario Galaxy 2
In Super Mario Galaxy 2, there are a total of 120 Green Stars to be found. These are only available once the player collects 120 regular Power Stars and then completes the first mission of Bowser's Galaxy Generator again. Each galaxy has the same number of Green Stars as regular Power Stars (except the Grandmaster Galaxy, which has no Green Stars at all, as collecting all of the Green Stars is required to unlock this galaxy). When collecting Green Stars, the player will have to do a certain mission of a galaxy again. In some cases the Green Stars in a galaxy can be collected in any order (e.g. "Green Star 2" can be collected during the Green Star 1 mission), but in general they can only be collected when playing a Green Star mission. Green Stars are usually found in hard to reach or hidden areas of the galaxies. Additionally, the Green Stars only appear when a galaxy is orbited by a Green Comet, which will appear once they are unlocked.

Super Mario Galaxy 2's Green Stars make a distinct twinkling sound, which is different from that of normal Power Stars and the Green Stars in Super Mario Galaxy and is meant to help players in locating them.

Super Mario 3D World / Super Mario 3D World + Bowser's Fury
Green Stars serve as the main collectible items in Super Mario 3D World and the Super Mario 3D World mode of Super Mario 3D World + Bowser's Fury. They function similarly to Star Medals from Super Mario 3D Land, and by extension, Star Coins from the New Super Mario Bros. games, and share the same sound effects as the former. All the regular courses have three of them, Enemy Battles have one, Captain Toad courses have five, and there can be five, ten, or thirty Green Stars in the Mystery Houses. In Enemy Battles, the player needs to defeat all the enemies to receive the Green Star. In main courses, they are scattered around in hidden areas just like Star Medals. In Captain Toad's Adventures levels, the objective is to solve the course's puzzles and to obtain all five Green Stars. In Mystery Houses, the player needs to complete one of the ten-second challenges to receive one. There are 380 Green Stars in total, and each of them additionally grants the player 4000 points. Some levels on the World Map require the player to have a certain number of Green Stars to play the level and advance past it.

Locked levels

 * Bowser's Highway Showdown - 10 Green Stars
 * Puffprod Peaks - 15 Green Stars
 * Chain-Link Charge - 30 Green Stars
 * Lava Rock Lair - 50 Green Stars
 * Backstreet Bustle - 80 Green Stars
 * Hands-On Hall - 100 Green Stars
 * Bowser's Lava Lake Keep - 130 Green Stars
 * The Great Tower of Bowser Land - 170 Green Stars
 * Cosmic Cannon Cluster - 210 Green Stars
 * Broken Blue Bully Belt - 240 Green Stars
 * World Crown - 342 Green Stars

Captain Toad: Treasure Tracker
Green Stars also appear exclusively in the Wii U version of Captain Toad: Treasure Tracker. After the end credits, a Green Star is falling across the sky that Captain Toad chases after. The star falls down the Clear Pipe leading to the Sprixie Kingdom from Super Mario 3D World which Captain Toad also enters. Green Stars also appear in the Super Mario 3D World levels in the Bonus Episode; however, instead of functioning like Super Gems (the equivalent item in the game), they replace Power Stars from regular levels at the end of a level, similar to the Super Mario Galaxy games.

The Green Star in the ending is replaced by the Odyssey in the Nintendo 3DS and Nintendo Switch versions to reflect the Bonus Episode this time being based on Super Mario Odyssey.

Super Mario 3D World

 * Instruction manual description: "Collect these and use them to unlock new courses."

Trivia

 * In Super Mario Galaxy, even though only three Green Stars are able to be recovered in the game, a total of seven Green Lumas can be found on the Comet Observatory and the Planet of Trials (counting the one that takes Mario to the Grand Finale Galaxy). Green Lumas grow up to become Green Stars, according to Polari.
 * When a Green Star mission is chosen in Super Mario Galaxy 2, the borders of the screen are green instead of black.

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