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Sonic News Network
Sonic News Network

The Egg Gravitron[1], also known as the Graviton Mobile[2][3] (グラビトンモービル[4] Gurabiton Mōbiru?), Doctor Robotnik's Energy Ship,[5] or Orb of Light,[6] is a vehicle that appears in the Sonic the Hedgehog series. It is a combat device created by Dr. Robotnik, who used it during the first part of the Angel Island incident.



The Egg Gravitron is an orange electrical mobile, which has four generators with dark green orbs on them that produce electricity. On the bottom, the Egg Gravitron has a heavy dark green ball that is used to create a magnetic pull with the electricity generators.

Features and abilities

The Egg Gravitron is capable of flight and can create a gravitational pull with its green ball and generators.


Sonic the Hedgehog 3 & Knuckles

In Sonic the Hedgehog 3 and the lock-on game Sonic the Hedgehog 3 & Knuckles, Dr. Robotnik used the Egg Gravitron in an attempt to destroy Sonic and Tails in Carnival Night Zone. However, the vehicle was destroyed by the heroes.

Other game appearances

Sonic the Hedgehog (Didj)

In Sonic the Hedgehog (Didj), the Graviton Mobile[2][3] was used by Dr. Eggman against Sonic in Hydropolis Zone. However, it ended up being destroyed.


The Egg Gravitron is the boss of Carnival Night Zone Act 2 in Sonic the Hedgehog 3 and Sonic the Hedgehog 3 & Knuckles, and the eighth boss overall. While in Sonic the Hedgehog 3 it is fought by Sonic and/or Tails, in Sonic the Hedgehog 3 & Knuckles it can also be fought by Knuckles if he takes the same route Sonic/Tails normally go through in the Act.

Boss guide

When the player enters the open arena, Dr. Robotnik appears from the right side of the arena in his Egg Gravitron and starts following the playable character from above. After some time, Dr. Robotnik will drop a large dark green globe on the ground and start hovering directly above it. He will then activate four generators on the side of the Egg Gravitron which will start rotating around it, creating a pillar of electricity that arcs downwards around the globe. This will turn it into an electromagnet for about seven seconds and will draw the player toward it, unless they are constantly moving away. Robotnik then descends to pick the globe up to repeat the pattern, which is the player's best chance to attack the Egg Gravitron. However, the dark green globe will damage the player if they touch it, as will the generators while they retract after hitting the Egg Gravitron.

The Egg Gravitron has a tendency to take a long time to defeat due to the limited chances to attack it relative to the duration of its attack pattern. Getting a Time Over can be the biggest problem when confronting this boss. There are several chances to land more hits on the Egg Gravitron unharmed by using Sonic's Insta-Shield at the right time or having a Lightning Shield. Tails can also damage the mobile from below while in flight.

After eight hits, the Egg Gravitron will be destroyed. The player will then be able to open the Capsule and complete the Zone.


EggRobo piloting the Egg Gravitron.

  • In Sonic the Hedgehog 3 & Knuckles, Knuckles usually skips this boss battle completely by taking the lower pathway, which only he can access at the start of Act 2. At the end of the Act, Knuckles ends up in the same room where he would send Sonic and/or Tails flying to the boss arena in their stories. Inside this room there is a Capsule and a teleporter that will transport the player to IceCap Zone after finishing the Act.
    • If the player takes Sonic and Tails' path via an upwards facing propulsion tube near the beginning of the Act, the Capsule won't appear, and Knuckles will need to climb up the tube to fight the boss. An EggRobo will be seen controlling the Egg Gravitron.
      • Beating the boss as Knuckles will cause cutscene mishaps, with Knuckles still being fired from the cannon at the end of Carnival Night Zone Act 2 to transition into IceCap Zone Act 1 but the latter act will still commence as if he used the teleporter that he uses at the end of Knuckles' usual route in the former Act.


Name Artist(s) Version Length Music Track
"Boss 2" Sega Sonic the Hedgehog 3/Sonic the Hedgehog 3 & Knuckles 1:14
Sonic & Knuckles Collection "FM Synthesizer" 1:09
"General MIDI" 1:05



Sonic the Hedgehog 3 Boss 8 - Graviton Mobile




  1. Flynn, Ian; Sega (8 December 2021). Sonic the Hedgehog Encyclo-speed-ia. Dark Horse Books. ISBN 978-1506719276. "Bosses: Act 2 - Egg Gravitron. Dr. Eggman draws you in with electromagnetic beams. Strike when he goes to retreive his focusing orb."
  2. 2.0 2.1 Sonic the Hedgehog (Didj) game design document, pg. 8.
  3. 3.0 3.1 Sonic the Hedgehog: Level 3 game hint. LeapFrog Community. Archived from the original on 12 June 2010. Retrieved on 1 April 2021.
  4. (in Japanese) ソニック・ザ・ヘッジホッグ3 公式ガイドブック. Shogakukan. 1 July 1994. p. 51. ISBN 978-4091024794.
  5. Sonic the Comic #37, "Sonic 3 Part 4 - The Bosses Cont'd"
  6. Hill, Simon (June 1994). "Carnival Night". The Official Sonic 3 Play Guide. Titan Books. p. 51. ISBN 1-85286-567-9. "End-of-Zone resistance comes in the form of Robotnik's spectacular ship, 'Orb of Light'."

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