Editing 1887: Two Down, One to Go

{{comic
| number    = 1887
| date      = September 8, 2017
| title     = Two Down, One to Go
| image     = two_down_one_to_go.png
| titletext = The third row will probably have to wait until 2034, and maybe longer. If I see a daytime supernova, I'll replace the meteor storm with that and consider it 3/3.
}}

==Explanation==
In this comic, [[Randall]] lists three of the most spectacular astronomical sights: a {{w|Solar eclipse|total solar eclipse}}, an {{w|aurora}} (Aurora Borealis in the northern hemisphere and Aurora Australis in the south), and a {{w|Meteor shower|meteor storm}}. In 2017, the first two of these phenomena happened within weeks of each other for observers in much of the US - a coincidence that Randall celebrates. 

* '''Total solar eclipse''': The {{w|Solar eclipse of August 21, 2017|total solar eclipse of August 21, 2017}} was the first seen for decades in the {{w|contiguous United States}}. Randall already made [[:Category:Total Solar Eclipse 2017|several comics about this eclipse]] and had traveled to Missouri to witness this for himself as shown in this comic: [[1880: Eclipse Review]].

* '''Aurora''': The aurora borealis is rarely visible from the continental USA. Randall bemoaned the fact he'd never seen one back in [[1302: Year in Review]] in 2013 - which also mentioned the 2017 eclipse. Randall likely finally saw it due to the [https://gizmodo.com/huge-solar-flare-disrupts-gps-satellites-1801838410 giant solar flares] in the week leading up to this comic probably without any need of traveling.

* '''Meteor storm''': A meteor storm is more than just a shower - while the best typical shower gives you a meteor or two per every minute, a storm gives you meteors every few ''seconds'' or better (or worse, depending on how you look at it). The {{w|Great Meteor Storm of 1833}} produced hundreds of thousands of meteors per hour. 

In the title text, Randall suggests the next meteor storm could be 2034, probably because this is predicted to be [http://adsabs.harvard.edu/full/2007JIMO...35....5M a good year for Leonids]. 

Randall then continues by saying that if he manages to see a {{w|supernova}} during the daytime, he will drop the goal for the meteor storm and call it 3 of 3. This is because such an event is so unlikely that he hasn't even included it in his bucket list, and he would be happy to switch between the two types of events if he had the chance. A few stars, when they turn supernova, could be so bright that they can be seen during the day time here  on Earth. The brightest supernova recorded in human history was {{w|SN 1006}} which was sixteen times brighter than {{w|Venus}} but still not bright as the full moon. {{w|SN 1054}} is an other example. When such an extremely rare event might happen is impossible to predict. There is a [http://earthsky.org/brightest-stars/betelgeuse-will-explode-someday (very small) chance]  that the giant star {{w|Betelgeuse}} will go supernova within Randall's lifetime, allowing him to tick this off the list too. Randall even mentioned that this could not happen soon enough in [[1644: Stargazing]]. Note that if you could see it during the day time, it would be one of the brightest objects in the night sky after the Moon.  Also keep in mind that if Betelgeuse were to go supernova in Randall's lifetime, he wouldn't see it since it's over 600 light years away.  For Randall to see it during his lifetime, it must have already gone supernova some 600 odd years ago, and we won't know that until we actually see it 613-881 years after it happened.

;Astronomical backgrounds
* This particular ''aurora borealis'' happened because the coronal mass ejection (CME) headed directly toward Earth causing Northern Lights spreading more south than common. That solar flare was first detected by the {{w|Solar Dynamics Observatory|Solar Dynamics Observatory (SDO)}} just eight minutes after it happened at the Sun. This [https://www.nasa.gov/feature/goddard/2017/nasa-s-sdo-captures-image-of-mid-level-flare animation] shows what the probe SDO has seen on Sept. 4, 2017 in the early evening. While light, and x-rays as well, travel at light speed the mass ejected did only move at a speed of 500-1,000 km/s. It was [http://www.swpc.noaa.gov/news/shock-arrival-6-sep-2308-utc-4-september-cme first detected] by {{w|Deep Space Climate Observatory|DSCOVR}} two days later, still 1,5 Mio. to reach Earth or just 30 minutes before the --non critical-- impact. And at this [http://www.swpc.noaa.gov/news/g3-watch-7-through-9-september-2017-due-cme-effects aurora forecast] the prediction showed that the northern United States were lucky.

* Betelgeuse is estimated to be in a range between 613 and 881 {{w|light-year}}s from Earth, which means that its light takes more than 600 years to reach Earth. That incident must have already happened when it should reach us in the next few decades. But since all information cannot travel faster than light{{Actual citation needed}} there is no way to find this out.
* Something about the brightness of celestial objects:
** The Sun is the brightest object at a {{w|Apparent magnitude|magnitude}} of −26.74
** The next object is the full moon at −12.90
** Venus is at −4.89 on maximum brightness, bright enough to be (barely) [http://www.fourmilab.ch/images/venus_daytime/ visible in the daytime]
** The mentioned supernovae SN 1006 and SN 1054 were at −7.50 and −6.00 respectively
** The brightness of the supernova from Betelgeuse is hard to predict. Because it's closer than both the other supernovae it could become brighter than Venus but definitely not than the full moon.

==Transcript==
:[There are three rows equally filled with squares and above are year dates beginning from 2002 until 2017. The first year (2002) is cut on the left and the color is light gray. It fades in to black, which it becomes in in 2005. To the left of the three rows the text reads:]
:Total eclipse
:Aurora
:Meteor storm
:[Below the year 2017 the squares in the first two rows are checked.]

{{comic discussion}}

[[Category:Total Solar Eclipse 2017]]
[[Category:Astronomy]]
[[Category:Solar eclipses]]