Comet Medal

“Collect many Comet Medals? Comet arrive. First time in galaxy... Always one Comet Medal somewhere! Look hard. Find!”

—Whittle, Super Mario Galaxy 2

Comet Medals are a type of item that appears in Super Mario Galaxy 2. They are white octagonal coins with a golden lining and a picture of a golden comet imprinted on them. Collecting enough Comet Medals will make Prankster Comets appear, like the Prankster Comets in the first game. They are found in the first mission of every galaxy, usually in hard to reach places or requiring the use of a power-up. Once collected, if the player re-enters the level, the Medal will appear to be a clear blue silhouette of the original. It can still be collected, however. It will temporarily be added to the total, but as soon as the level is completed, the total will revert back to its previous value.

There are 49 Comet Medals total, but not every galaxy will encounter a Prankster Comet, even after every Comet Medal has been collected.

Comet Medal Locations

World 1
Galaxy	Comet Medal Location
Sky Station Galaxy	High above the cylindrical planet with gray platforms rotating around it, it opens Peewee Piranha's Speed Run.
Yoshi Star Galaxy	On a small green hill in the area where the player first obtains Yoshi, it opens Spiny Rainbow Romp.
Spin-Dig Galaxy	Next to the right-most pillar on the Drill Zone Planet, it opens Digga-Leg's Daredevil Run.
Fluffy Bluff Galaxy	Above a column of coins on the Pond Planet. Cloud Mario is needed, or a triple jump or back-flip and spin at the apex of the jump, Fluffy Bluff has no Prankster Comet of its own until the Green Stars are unlocked.
Flip-Swap Galaxy	On a blue platform near the end of the first area, it opens Purple Coin Flip 'n' Sprint.
Rightside Down Galaxy	Between two Thwomps in an upside down section, just after the Chomps, Rightside Down has no Prankster Comet of its own until the Green Stars are unlocked.
Bowser Jr.'s Fiery Flotilla	Above the Thwomp near the beginning of the stage, it unlocks Fiery Flotilla Speed Run.
World 2
Galaxy	Comet Medal Location
Puzzle Plank Galaxy	Off to the side of a wooden platform, just before two Grinders cut off a vertical wall, which creates an area that Mario must wall-kick up, it unlocks Purple Coin Shadow Vault.
Hightail Falls Galaxy	Near the end of the level right after the Hungry Luma, it unlocks Hightail Falls Speed Run.
Boulder Bowl Galaxy	Right at the beginning of the level inside the purple crystal. Rock Mario is needed, it unlocks Rolling Crabber Romp.
Cosmic Cove Galaxy	Inside a large shell-shaped structure underwater, near the button that freezes the entire area, Cosmic Cove has no Prankster Comet of its own until the Green Stars are unlocked.
Wild Glide Galaxy	Obtained after going through the five gates, Wild Glide has no Prankster Comet of its own until the Green Stars are unlocked.
Honeybloom Galaxy	On a small platform guarded by a Choppah, Honeybloom has no Prankster Comet of its own until the Green Stars are unlocked.
Bowser's Lava Lair	Reached by wall-jumping or Backflipping off a Whomp, it unlocks Lava Lair Speed Run.
World 3
Galaxy	Comet Medal Location
Tall Trunk Galaxy	On the Log Planet, it unlocks Tall Trunk's Purple Coin Slide.
Cloudy Court Galaxy	Near the end of the level inside the crushing wall, it unlocks The Shadow Lining.
Haunty Halls Galaxy	Over a large gap, just after a green pipe, it unlocks Spooky Cosmic Clone Chase.
Freezy Flake Galaxy	Hidden beneath some Brick Block-shaped snow, on the third planet after the slide, Freezy Flake has no Prankster Comet of its own until the Green Stars are unlocked.
Rolling Masterpiece Galaxy	Near the end on a platform about to be cut by Grinders, it unlocks Masterpiece Speed Run.
Beat Block Galaxy	Near the beginning on top of an orange Beat Block, it unlocks Silver Stars in Double Time.
Bowser Jr.'s Fearsome Fleet	On the Airship with the Hammer Bros, just before Mario fights Megahammer, it unlocks Megahammer's Daredevil Bash.
World 4
Galaxy	Comet Medal Location
Supermassive Galaxy	At the start of the level, over a large gap in the middle of an arc of coins, near the large spinning coin and a Grand Goomba, it unlocks Big Wigglers Speed Run.
Flipsville Galaxy	On the first planet on the underside of it, it unlocks Purple Coin Spin Speed Run.
Starshine Beach Galaxy	Only in the underwater area of the mission "Surf, Sand, and Silver Stars", between two Gringills, it unlocks Purple Coin Beach Dash.
Chompworks Galaxy	At the beginning of the level, over the Chomps, it unlocks Cosmic Clones in the Chompworks.
Sweet Mystery Galaxy	In a secret platform that appears with Bulb Yoshi, it unlocks Bulb Berry's Purple Coin Glow.
Honeyhop Galaxy	In a set of two walls. It requires wall-jumping, Honeyhop has no Prankster Comets of its own until the Green Stars are unlocked.
Bowser's Gravity Gauntlet	Near the checkpoint flag in the castle. On top of the Brick Block, it unlocks Gravity Star Speed Run.
World 5
Galaxy	Comet Medal Location
Space Storm Galaxy	Between to an electric fence and set of platforms going down, Space Storm has no Prankster Comets of its own until the Green Stars are unlocked.
Slipsand Galaxy	On a small patch of solid ground where the sand river bends, it unlocks Squizzard's Daredevil Run.
Shiverburn Galaxy	Hanging over the moving stone platforms of the lava planet, it unlocks Octo-Army Icy Rainbow Romp.
Boo Moon Galaxy	In the swamp right next to the launch star, Boo Moon has no Prankster Comets of its own until the Green Stars are unlocked.
Upside Dizzy Galaxy	Under an electrified fence and over a moving platform, Upside Dizzy has no Prankster Comets of its own until the Green Stars are unlocked.
Fleet Glide Galaxy	Obtained after flying through the five gates, Fleet Glide has no Prankster Comets of its own until the Green Stars are unlocked.
Bowser Jr.'s Boom Bunker	On the mine-lined blue row on the spindly planet, it unlocks Boomsday Machine Daredevil Run.
World 6
Galaxy	Comet Medal Location
Melty Monster Galaxy	On one of the lava-burned planetoids hanging over the Magmaw planet, Melty Monster has no Prankster Comets until the Green Stars are unlocked.
Clockwork Ruins Galaxy	Hanging above the cogs rolling down the first slope, it unlocks The Adventure of the Purple Coins.
Throwback Galaxy	Found in the exact same spot from where the "Shoot Into the Wild Blue" Power Star from Super Mario 64 used to be, it unlocks Whomp Silver Star Run
Battle Belt Galaxy	Right above a lava pool on the burn bit planet, it unlocks Mini-Planet Daredevil Run
Flash Black Galaxy	Found at the top left corner of the planet where Yoshi is found, it unlocks Dark Octo-Army Romp.
Slimy Spring Galaxy	After sliding down the water slide, in the first room with Snoodles, the Comet Medal is located in a small alcove on the left side of the room, just before the next tunnel, Slimy Spring has no Prankster Comet of its own until the Green Stars are unlocked.
Bowser's Galaxy Generator	With Yoshi's assistance, the Comet Medal can be found on the lava on the left moving path, next to two flowers, it unlocks Bowser's Big Bad Speed Run.
Special World
Galaxy	Description
Mario Squared Galaxy	This Comet Medal is located on Mario's left foot, on disappearing platforms, it unlocks Luigi's Purple Coin Choas.
Rolling Coaster Galaxy	This Comet Medal is located on the expert path. After the Toad says "Experts stay right", go down the right path until seeing the Comet Medal and two Bob-ombs. It should be just before the other path crosses back into the course, it unlocks Purple Coins on the Rainbow Road.
Twisty Trials Galaxy	This Comet Medal is located at the end of the second to last spinning block (Just before the star), it unlocks Turning Turning Double Time.
Stone Cyclone Galaxy	This Comet Medal can be seen right from the start. However, it's right above one of the platforms that move left and right. (Closest to the Black Hole), it unlocks Tox Box Speed Run.
Boss Blitz Galaxy	Underneath the King Kaliente battlefield, it unlocks Throwback Throwdown Speed Run
Flip-Out Galaxy	Above the first blue platform when the player is in the second area of spikes, it unlocks Cosmic Clone Wall Jumpers.
Grandmaster Galaxy	Next to one of the platforms on the right side, in the area filled with Hammer Bros. and Boomerang Bros, it unlocks The Perfect Run.

Trivia

• When collected, the Comet Medal makes a similar sound effect to that of a Red Coin from Super Mario Sunshine.
• They were originally thought to be known as Comet Metals due to a mistranslation.
• Comet Medals have a shape that is almost identical to the shape of the Spaces from Mario Party 6.
• The Star Medals in Super Mario 3D Land for the Nintendo 3DS feature a design similar to that of Comet Medals.