Daytime moon

[Mendel]

The sun has gotten brighter in the past few years... it's been getting steadily brighter for millions of years, after all.

and we had ice ages anyway

 

[John J.]

The sun has gotten brighter in the past few years... it's been getting steadily brighter for millions of years, after all.

Well yes, the Sun is gradually brightening as it creeps along the Hertzsprung-Russell diagram

-but that doesn't mean it is invariably brighter each year (or appreciably brighter over decades).
The Sun's output has decreased slightly in recent years, with the ending of solar cycle 24.

At present, it is increasing in brightness by about 1% every 100 million years.

Wikipedia, Sun

The very gradual, inexorable brightening as the Sun ages is much, much less in any given year (or few decades) than the changes in luminosity (both increased and decreased solar activity) that occur as part of shorter-term variations, e.g. in connection with the 11-year (approx.) sunspot cycle:

Solar output is nearly, but not quite, constant. Variations in total solar irradiance (TSI) were small and difficult to detect accurately with technology available before the satellite era (±2% in 1954). Total solar output is now measured as varying (over the last three 11-year sunspot cycles) by approximately 0.1%...

Wikipedia, Solar constant

...so there is approx. as much variation in solar output over 33 years as there is expected brightening over 10 million years.

Changes in solar irradiance over the 11-year solar cycle have been correlated with changes in sunspot number. The solar cycle influences space weather conditions, including those surrounding Earth. For example, in the 17th century, the solar cycle appeared to have stopped entirely for several decades; few sunspots were observed during a period known as the Maunder minimum. This coincided in time with the era of the Little Ice Age, when Europe experienced unusually cold temperatures. Earlier extended minima have been discovered through analysis of tree rings and appear to have coincided with lower-than-average global temperatures.

Wikipedia, Sun

There are other theories about the cause of the Little Ice Age, but the correlation with the Maunder minimum is striking.
It implies (as do other minima, and carbon-14 records) that variations in solar activity can be greater, and longer-lasting, than the 0.1% in the past 3 sunspot cycles; the mechanisms behind this are not well understood.

There was (as part of normal variation) an increase in solar activity in the early to mid- 20th century, followed by a reduction in recent years:

The Modern Maximum was found by Sami Solanki, Ilya G. Usoskin and colleagues as the period of unusually high solar activity which began with solar cycle 15 in 1914. It reached a maximum in solar cycle 19 during the late 1950s and may have ended with the peak of solar cycle 23 in 2000, as solar cycle 24 is recording, at best, very muted solar activity. Another proposed end date for the maximum is 2007, with the decline phase of Cycle 23. In any case the low solar activity of solar cycle 24 in the 2010s marked a new period of reduced solar activity.

Wikipedia, Modern Maximum

The long-term trend is that the Sun is brightening, but that doesn't mean the Sun is brighter each year (or even each successive decade).

 

[Ann K]

The sun has gotten brighter in the past few years... it's been getting steadily brighter for millions of years, after all.

Well...not a lot. Graph of the last 400 years based on sun spot observations:

https://www.climate.gov/graph-dashboard-suns-energy-total-solar-irradiance

 

[FatPhil]

Well...not a lot. Graph of the last 400 years based on sun spot observations:
View attachment 81040
https://www.climate.gov/graph-dashboard-suns-energy-total-solar-irradiance

Given "Variations in total solar irradiance (TSI) were small and difficult to detect accurately with technology available before the satellite era (±2% in 1954)." the appropriate measurement error regions on that diagram would colour everything between 1335 and 1390 in grey, surely? (Or what else is @John J.'s quote trying to actually say?)

If they'd have drawn their error bars in in the first place, I wouldn't be needing to ask this question, grrrr.

 

[John J.]

Given "Variations in total solar irradiance (TSI) were small and difficult to detect accurately with technology available before the satellite era (±2% in 1954)."

Graph of the last 400 years based on sun spot observations:

Some thoughts on the graph: Irradiance is shown to increase in the early 20th century, peaking in the late 1950s/ early 1960s roughly as described by the Modern Maximum.

It looks like average irradiance has been higher since the 1950s than earlier, but this coincides with more accurate measurements since 1954. -The very recent uptick on the graph might contradict the Wikipedia, Modern Maximum claim of "a new period of reduced solar activity"; if so, I'd trust the NOAA figures (i.e. the graph) more than Wikipedia.

So in fairness to @FoxRoom (a belated welcome! Hope you have fun here, and find lots of interesting stuff) someone could point to the NOAA graph and say the Sun is brighter now than in recent years (or anytime since c. 1610 - or maybe 1954 ).
I doubt it would be perceptible though,

Similar to the folks who think the Sun is now brighter and more white than they remember from childhood...

I doubt those same folks (if they're old enough), relying on their memories, would be able to identify years of low solar irradiance and high solar irradiance, which correlate with the sunspot cycle, yet that variation (up and down) in irradiance is much more than the increase that might be expected from the Sun's intrinsic brightening over a few decades.

At present, it [the Sun] is increasing in brightness by about 1% every 100 million years.

Wikipedia, Sun
This corresponds fairly well with how much the Sun is believed to have brightened in the past,

since the beginning of its main sequence life, it has expanded in radius by 15% and the surface has increased in temperature from 5,620 K (9,660 °F) to 5,772 K (9,930 °F), resulting in a 48% increase in luminosity from 0.677 solar luminosities to its present-day 1.0 solar luminosity.

(Wikipedia, as above):
The Sun is 4.6 billion years old, a 1% brightening x 46 (100 million year spans) = a 46% increase in luminosity from start of main sequence to now (very approximately. I don't know if compound interest applies )

There is a trend to solar brightening, but it is slow and subtle. If it is averaged out, it is approx. 0.00000001% per year.
This is much less than the variation of 0.1% (presumably 0.05% above and below the mean solar constant) which is experienced over years and decades. If events like the Little Ice Age are caused by changes in solar irradiation, as perhaps indicated by the Maunder minimum, it seems likely that there are periods of at least a few decades where solar output is maintained at the lower end of normal variation, or perhaps less (equally, periods where output is sustained at the upper end, or perhaps more).

Scientists are still debating whether or not the Sun's activity increased during the latter half of the 20th century, but even the highest estimates of activity can't account for the [Earth's] warming observed since about 1950.

Studies do show that solar variability has significantly influenced past climate changes. For example, a decrease in solar activity is thought to have triggered the Northern Hemisphere's Little Ice Age between approximately 1650 and 1850

NASA, "earth observatory" website

Or what else is @John J.'s quote trying to actually say?

An excellent question, which I often ask myself...

Basically,
(1)

...the folks who think the Sun is now brighter and more white than they remember from childhood

are probably wrong, as solar variation of the order so far measured probably isn't directly perceptible*- most people can see the Sun, but we've only had reliable measures of its output since 1954.
I'm not aware of 17th/18th/19th century astronomers recording a change in solar luminosity or colour, but they did record a reduction, and return, of sunspot activity, which we know is a useful proxy for solar irradiance.
AFAIK the people claiming that the Sun appears brighter don't claim to remember perceiving the changes in solar output that we know happens e.g. in connection with the 11-year sunspot cycle.

(2)

The sun has gotten brighter in the past few years... it's been getting steadily brighter for millions of years, after all.

The Sun is brightening, but it isn't necessarily brighter in each consecutive year or decade- even century (Maunder minimum).
Solar irradiance is subject to variations much larger, in the short term, than the increase due to evolutionary brightening.

It's a bit like the much more immediate problem of anthropological climate change: The Earth is warming due to our greenhouse gases, but that doesn't mean each subsequent year will always be hotter than the last.
Climate change deniers sometimes point out that not every year in recent times is hotter than its predecessor.
However, the trend is upward (and much more rapidly than the trend for increased solar irradiance).

______________________________________________________________________________________________________________________________________
*Maybe some of these people live in areas where there's less haze due to coal-burning etc.? That might depend on them being a certain age, though- and having extraordinarily accurate memories.

Edited to add: As for the Sun appearing whiter (as opposed to brighter), I'd guess there are records of the Sun's spectra going back further than the memories of the "brighter and whiter" claimants.

 

[jdog]

In the short term, the biggest and most regional variable to the received radiance of the sun will likely be aerosols in the atmosphere, whether from natural sources like volcanic outgassing or Saharan dust (a batch of which is currently on its way to Florida) or industrial pollution.

The skies used to be quite polluted in industrialized nations, enough to cause global dimming -- decent summary at https://en.wikipedia.org/wiki/Global_dimming -- which may have offset some global warming in the mid-20th century. So it's possible the sun's appearance has changed for some people, though I'm doubtful it was enough to be distinctly memorable.

 

[Ann K]

In the short term, the biggest and most regional variable to the received radiance of the sun will likely be aerosols in the atmosphere, whether from natural sources like volcanic outgassing or Saharan dust (a batch of which is currently on its way to Florida) or industrial pollution.

The skies used to be quite polluted in industrialized nations, enough to cause global dimming -- decent summary at https://en.wikipedia.org/wiki/Global_dimming -- which may have offset some global warming in the mid-20th century. So it's possible the sun's appearance has changed for some people, though I'm doubtful it was enough to be distinctly memorable.

Many years ago (probably 40 or more) I attended a lecture in which the speaker (alas, now forgotten) said that the astronauts on the early Mercury spaceflights were asked to take a photo of Africa "if they had a chance to see a Sahara dust storm", but some years later the directive was given to take a picture of Africa "if they had a chance to see it without a dust storm". No, I cannot verify that, but the words stuck in my mind as evocative of the changes to our world.