Scientists still hope that Comet ISON will brilliantly pass by the Earth despite losing material in its close pass of the sun late in November. The comet was predicted to be one of the brightest in at least one hundred years, but has not lived up to its prediction so far. It was expected to “slingshot” the sun and become brighter as it headed back out of solar system. But, many astronomers have doubts as to whether or not the comet has sufficiently survived its close encounter with the sun to make it back out of the solar system intact.
The comet has been reported dead, then back to life, then dead again several times over the last week. Karl Battams, an Astrophysicist at the Naval Research Laboratory stated on Twitter: “I *do* think that something emerged from the Sun, but probably a very small nucleus or "rubble pile", and I fear that may have now dissolved...”. However, a series of special satellites that study that sun (known as STEREO) has noted something emerging from the area with a comet-shaped tail, so hope remains. Part of the problem was that the comet seemed to have disappeared for a short time, so it wasn’t certain what happened to it.
If Comet ISON is still viable, it should be expected to pass by the Earth during December. Depending on how much of the comet is intact, it is expected to be at its brightest during this month as it heads out of the solar system. Currently, the comet (or parts of it) are still close to the sun and are difficult to see in the daytime. By the end of the week, it should be visible in the San Diego area in the northern sky, but it is unknown how bright it will be. Most likely it will not be as bright as expected due to loss of size. Though it will be visible throughout most of the world, the northern hemisphere will get the best look between now and Christmas Day.