What Powers the Brightest Objects in the Universe?

 

The brightest object in the universe is a quasar. Now what is quasar? It is like headlight of a car (galaxy) where supermassive black hole(SMBH) is the engine of that car. It's the best simple way to analog galaxy, supermassive black hole and quasar. So that SMBH Powers the brightest object.

When matter infalling to a black hole, it spirals and forming an accretion disc. For friction and spinning property of black hole, this region's temperature goes to million to billion kelvin. At centre where quasar is, gravity turns into light and high velocity (nearly equal to velocity of light)relativistic jets are emerged. That quasar for milky Way galaxy is 1000 times brighter than that of milky way itself. It can shine whole galaxy.

So the answer is SMBH powers the brightest object (Quasar)in the universe.

Image source: google

Vishnu has 4 arms and holds 4 objects. What are those objects?

 The four objects in the 4 arms of Vishnu are Shankha, Chakra, Gada, Padma or in simplified English equivalents they are Conch, Discus, Mace and lotus.

Now, which arm of Vishnu holds which object? That is an interesting question. The Dwaita philosopher Madhvacharya lists out 24 ways ( i.e. 4X3X2X1) of holding these objects in 4 arms, in his Tantrasara Sangraha. Accordingly, each form (Roopa) holding the objects in a specific way is given a name and worshiped for a specific purpose. These 24 forms (Roopa) are

1. Keshava : Shankha, Chakra, Gada, Padma (clockwise starting from the top right hand)
2. NarayaNa: Padma, Gada, Chakra, Shankha
3. Madhava: Chakra, Shankha, Padma, Gada
4. Govinda: Gada, Padma, Shankha, Chakra
5. VishNu: Padma, Shankha, Chakra, Gada
6. Madhusoodhana: Shankha, Padma, Gada, Chakra
7. Trivikrama: Gada, Chakra, Shankha, Padma
8. Vaamana: CHakra, Gada, Padma, Shankha
9. Shreedhara: Chakra, Gada, Shankha, Padma
10. Hrsheekesha: Chakra, Padma, Shankha, Gada
11. Padmanaabha: Padma, Chakra, Gada, Shankha
12. DaamodaraL Shankha, Gada, Chakra, Padma
13. SankarShaNa: Shankha, Padma, Chakra, Gada
14. Vaasudeva: Shankha, Chakra, Padma, Gada
15. Pradyumna: Shankha, Gada, Padma, Chakra
16. Aniruddha: Gada, Shankha, Padma, Chakra
17. PuruShottama: Padma, Shankha, Gada, Chakra
18. AdhokShaja: Gada, Shankha, Chakra, Padma
19. Narasimha: Padma, Gada, Shankha, Chakra
20. Achyuta: Padma, Chakra, Shankha, Gada
21. Janaardhana: Chakra, Shankha, Gada, Padma
22. Upendra: Gada, Chakra, Padma, Shankha
23. Hari: Chakra, Padma, Gada, Shankha
24. KrShNa: Gada, Padma, Chakra, Shankha

Following image shows the 24 ways in which Udupi Krishna - the Krishna installed by Madhvacharya at Udupi - is decorated to illustrate the 24 forms of Vishnu as explained above.

What is the maximum size limit for objects in space?

 Well. There’s the biggest star we have seen to date:

Size comparison of a hypothetical quasi-star/black hole star (diameter of ~10 billion kilometres or ~7,187 solar diameters, mass of 1000+ solar masses) and several known giant stars: Stephenson 2-18 (~2150 solar diameters), VY Canis Majoris (~1420 solar diameters, ~17 solar masses), Betelgeuse (~887 solar diameters, ~11.6 solar masses), the Pistol Star (~306 solar diameters, ~27.5 solar masses), Rigel (~78.9 solar diameters, ~23 solar masses), and R136a1 (~35.4 solar diamaters, ~265 solar masses). Image credit: Wikimedia Commons/Sauropodomorph (CC0 1.0)

And then there’s the biggest black hole to date:

The largest black hole ever discovered. Estimates of its mass and size make this black hole a true behemoth, and it is unlike anything in our galaxy or in any of the galaxies in our galactic neighborhood. The mass of the central black hole is estimated to be 100 billion times larger than the sun. The supermassive black hole is even more massive than some galaxies, and is about 10% the mass of the entire Milky Way. The event horizon of the black hole has a diameter of 590 billion kilometres, or about 100 times the distance between the sun and Pluto. That little dot in the middle is the orbit of Neptune.

And then there’s the largest galaxy discovered to date:

Its full span is 5.5 million light-years across: nearly double the Local Group’s full extent.

Then there’s superclusters of galaxies:

Finally, there’s Quipu:

The colored dots represent different superstructures out to 800 million light-years from Earth. The red dots denote Quipu, the largest known structure in the nearby universe. Yellow is Sculptor-Pegasus superstructure, green is Serpens-Corona Borealis, purple is Hercules and blue is Shapley. Image via Böhringer et al. Astronomy and Astrophysics, 2025.

There are 185 galaxy clusters within these five superstructures. Quipu alone has 68 galaxy clusters.

How tiny is the earth compared to other celestial objects in space?

 Solar system planets:

Now, if you add Sun:

And compare it to bigger stars:

And compare those stars to even bigger stars:

This would give you perspective and show how tiny the earth is in comparison to everything else.

What is the largest object in the universe?

 If you mean a singular object instead of clusters of stars (galaxies) or clusters of galaxies (superclusters), then I will provide my list (that we know of so far):

Largest non-spherical solid object: Haumea - 620 km radius.

Largest moon: Ganymede - 2634 km radius.

Largest rocky planet: Kepler 10 c - 2.35 Earth radii (15,000 km).

Largest gas giant planet: HD 100546 b - 6 Jupiter radii (419,466 km).

Largest ring system: J 1407 b - 0.6 AU radius (90 million km).

Largest star: UY Scuti- 1708 Solar radii (1.19 billion km).

Largest black hole: TON 618 - 1300 AU radius (194.5 billion km).

Largest (mostly intact) nebula: LAB-1–300,000 light year diameter.

As mentioned before, as a bonus:

Largest galaxy: IC 1101- 3.92 million light year diameter.

Largest structure: Hercules-Corona Borealis Great Wall - 10 billion light year diameter.

UPDATE 2020:

Stephenson 2-18 is now considered to be among the largest known stars, if not the largest, with a radius of 2,158 solar radii. UY Scuti on the other hand is about 1,700 times greater than the radius of the sun. It is also among the most luminous cool supergiant stars, with a luminosity of 440,000 solar luminosity.

Update 2023:

The largest black hole discovered so far is Phoenix A from the Phoenix Cluster. It is around 100 billion times the mas of the Sun and has an astounding radius of around 1950 Astronomical Units (295.25 billion kilometers).