 Greetings and welcome to the Introduction to Astronomy. In this week's Misconception in Astronomy we are going to look at Jupiter and try to decide, is Jupiter close to being a star? Are we very close to living in a double star system? Well, let's take a look. What do we know about Jupiter? Well, is Jupiter nearly a star? Well, quick answer, no. Jupiter is way too little mass to be close to being a star. What do we mean by a star? Well, a star is something that fuses hydrogen into helium in its core. Well, how is Jupiter excluded from this? Well, it takes a certain amount of mass for this to occur. You have to have a high enough temperature at the core and in fact of 10 million Kelvin. So you need a temperature of 10 million degrees minimum for an object to be a star. In order to get high enough pressures to get this kind of temperature in the center you would need at least 80 Jupiter masses. So Jupiter is not close to being a star. What does that mean? Well, Jupiter, even if you took all of the other material in the solar system. So we have our sun, let's ignore that. But if we took Jupiter and all of the other planets and all of the asteroids and all of the comets and all of the other debris in the solar system and put that together, we still wouldn't even be close. We'd still be struggling to get two Jupiter masses, let alone 80 to make it a star. So, quick answer, Jupiter is not a star and not even close. But let's take a look at what some of these other objects are. So we have, we can divide objects into one of three things. We can have stars which are fueled by nuclear fusion. That's what we've looked at here. Those are at least 80 times Jupiter's mass. We have an intermediate object called a brown dwarf. So these are objects that are not enough mass to fuse hydrogen but they can fuse deuterium. Deuterium is a heavy form of hydrogen. It's hydrogen with one proton, which all hydrogen atoms have, but also one neutron, so it's a heavier version of hydrogen. And it's a little bit easier to fuse together. You only need about a million kelvins to be able to do that. So if you had something of about 13 to 80 Jupiter masses, you would have a brown dwarf. Again, that's still far more massive than Jupiter to the rest of the material within our solar system. And then you have things like planets. Planets are far too cool for any kind of nuclear reactions at all. And those are masses of 13 Jupiter masses or less. So this is where Jupiter falls. Jupiter is very definitely a planet. It is not close to being a brown dwarf and it is nowhere near being large enough to actually undergo nuclear reactions in its core to become a star. So no, regardless of what you might like to think, we are nowhere near being in a double star system. So let's go ahead and look at our summary here. And what we've looked at is, again, Jupiter nowhere near massive enough to be a star. It would need 80 Jupiters. And if we took all of the material into the solar system and added that to Jupiter, we would not even reach the brown dwarf stage, let alone a star. So that concludes this week's discussion on whether Jupiter is close to being a star. We'll be back again next time for another misconception in astronomy. So until then, have a great day, everyone. And I will see you in class.