# The Sun and Space Weather
## 10 Concluding Remarks  
We have a fairly good understanding of large space weather events that can be linked to solar eruptions from magnetically closed regions and coronal holes. The electromagnetic component of solar eruptions is the solar flares that have prompt response in the form of magnetic crochet and sudden ionospheric disturbances. It takes only \(\sim\)8 min for the X-ray photons to reach Earth's atmosphere. Closely following flares are GLEs that are delayed only by a couple of minutes. CME-driven shocks, on the other hand, take anywhere from half a day to a few days to reach Earth and cause SSC or sudden impulse. Thus, the timescales involved range from minutes to a few days. Accordingly the predictability of flares, SEPs, and CME/shock arrival differ significantly [195]. While predicting flare/CME occurrence based on source region properties is a long way away, there are methods being developed actively using statistics and machine learning (see [196] and references therein). Predicting SEP events also needs to be probabilistic in nature [197; 198]. Methods of predicting SEP occurrence based on neural networks are being actively pursued (see e.g., [199] and references therein). The statistical result that spacecraft anomalies peak a couple of days after the start of an SEP event (see Figure 17) can be used to predict certain impacts after detecting a GLE event, because the GLE and SEP intensities are correlated [200]. Similarly, predicting the shock arrival (SSC) at 1 au [201] has value, because spacecraft anomalies also peak a couple of days after SSC (see Figure 18).  
We have mainly considered the space weather consequences of solar eruptions and coronal holes. We have not considered CME initiation or the trigger of eruptions [202; 203; 204; 205]. The discussions in this paper are concerned with the mature stage of CMEs after the completion of magnetic reconnection in the eruption region [206]. The mature flux rope that follows after the initial seed flux rope becomes unstable and initiates the flare reconnection [207]. The seed flux rope can be hot [208] or cold (associated with a filament) [209; 210]. We have also not discussed another aspect of CMEs and CIRs, viz., the Forbush decrease (see [211; 212; 213] and references therein), nor the overall increase in cosmic ray flux due to weak solar activity [214].  
The solar and heliospheric community has made enormous progress in understanding solar magnetic variability and its impact on the inner heliosphere, especially on Earth's space environment. The progress can be attributed to the rapid advances in space missions  
Figure 25: (**a**) Cumulative distribution of CME sky–plane speeds (V) from [[https://cdaw.gsfc.nasa.gov/CME_list](https://cdaw.gsfc.nasa.gov/CME_list)]([https://cdaw.gsfc.nasa.gov/CME_list](https://cdaw.gsfc.nasa.gov/CME_list)), (accessed on 1 October 2022), with the average speeds of various CME populations. The original data is binned into 5 data points per decade. (**b**) Weibull (blue) and power law (red) fits to the CME speed distribution. Updated from [191].  
that culminated in SOHO and STEREO. Recent observatories, such as the Parker Solar Probe and the Solar Orbiter, have started aiding deeper investigations of solar variability. Data from multiple views of the Sun from vantage points away from the Sun-Earth line (L4 and L5, polar orbit), coupled with global MHD modeling, are expected to rapidly advance our knowledge of solar magnetic variability.  
This research was funded by NASA's Living With a Star program.  
Not applicable.  
All data used in the article are publicly available and the URLs provided.  
This review article benefited greatly from NASA's open data policy in using SOHO, STEREO, and SDO data. I thank [PERSON] and [PERSON] for help with some figures and [PERSON] for formatting the references according to the journal style.  
The author has no conflict of interest.