Looking for the perfect spot to watch the children's parade at 10?
Then you are in luck. At 10am on 17 May the sun comes almost exactly
straight up Karl Johans gate — 37 degrees above the horizon, from the
south-east, along the street rather than across it. That is why very nearly the whole route
is lit at once, and why the palace facade takes the light full in the face while the royal
family waves.
The sun at 10am
We worked out the sun's position over Oslo on 17 May at 10.00 Norwegian time, with the
same code Soltreff uses in every report it makes: azimuth 118 degrees
(clockwise from true north, so 0 is north and 90 is east) and
37 degrees above the horizon.
Karl Johans gate runs at 299 degrees — that is 119 degrees if you
stand at Jernbanetorget and look up towards the palace. The sun at 10am sits
one degree off that line. It comes from directly behind you as you
walk up towards the palace.
That is not a curiosity, it is the whole answer to where you should stand. When the sun
lies along a street instead of across it, the rows of buildings do not throw
shade into the street — they throw it along themselves. We measured it: across
80 points on the carriageway, along the whole of Karl Johans gate, at
eye height 1.7 metres, 79 are in direct sun at 10am. The one that is
not sits where the horizon in the sun's direction reaches 37.1 degrees — a tenth of a
degree above the sun. That is inside the sun disc's own width, so strictly that point is
a tie rather than shade. The tightest of the other 79 has 5.6 degrees to spare — twenty
times the disc's own radius — so the rest are nowhere near borderline.
So neither side of the street is the “right” one at 10am. It is a
rare situation, and it does not last long.
Is the balcony in sun?
Yes. And the direction is worth establishing, because it is not the one people guess:
the palace's front faces south-east, not east. We derived the facades
from the building's own outline and got three wall surfaces at 120.0,
120.0 and 120.1 degrees — a good hundred metres of
wall in total, all pointing the same way. The front looks straight down Karl Johans
gate, to within about a degree.
The sun at 10am sits between 1.9 and 2.1 degrees from the direction
those three surfaces face. It strikes the front almost square on. The horizon seen from the facade is
between 1.2 and 2.8 degrees in the sun's direction — that is the park
and Slottsplassen, sloping down and away — while the sun stands at 37. Nothing is in
the way, at any height we calculated. The balcony is in sun.
And at noon?
By then it has turned. At 12.00 the sun stands at 154 degrees and
47 degrees up: it has swung 36 degrees south and no longer lies along
the street but at an angle across it. The same 80 points on the carriageway now give
58 in sun and 22 in shade — the row of buildings on the south side has
begun to lay shade inwards. The palace facade is still lit at every height above ground
level, but the ground plan of two of the three front wall surfaces has fallen into
shade from the palace's own projecting wings.
The report for Slottsplassen 1
The palace is an address Soltreff answers for. The card below is the report the service
gives for Slottsplassen 1, taken from the running service and set here
as text: the south-east front (120 degrees) gets 1,687 hours of direct sun a
year at ground level and 38–76 minutes on 21 December, above
the building's median of 1,338 hours. The moment is set to 17 May at 10am, and the
report says what the figures above say: the sun is on the facade, 37 degrees above the
horizon.
Slottsplassen 1, Oslo municipality · Public building · ground plan: on facade SE (120°) · 38 m, this floor gets roughly 1,687 hours of direct sun a year — above the building median.
Direct sun per year1,687 h
21 December38–76 min
Openness5.9 / 10
How much of the sun that could have reached this wall actually gets through. 10 means almost nothing is in the way — neither neighbours nor trees.
Sun index4.9 / 10
The sun here, measured against a south-facing wall with nothing in the way at the same latitude. 10 is what such a wall would get; both the direction the wall faces and the surroundings pull it down.
Spread across the year
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
sun1. outbuilding/garage and trees2. building and trees3. building and treesother obstructions
What does the height of the bars show?
The height is the hours the sun is up and in front of this wall, not the whole day length. A wall sees about half the sky, so the summer sun is up for hours behind the wall without counting here. That is also why the steps between months are uneven: a roofline is a threshold, not a gradual change. The month the sun clears it, a whole slice of the day goes from shade to sun at once.
↑ 04:42 · ☀ 13:12 · ↓ 21:48
17h 06m above the horizon
7h 06m of direct sun on this facade
17 May, 10:00
The sun is on the window, 37° above the horizon.
Worked out from the stored horizon for this wall and floor, without clouds. In practice the changeover between sun and shade is soft by a couple of minutes either way. The time is Norwegian local time.
Compared with the building
The building median is 1,338 hours. The middle half falls between 765 and 2,286 hours.
What takes the sun?
The obstructions are measured in the laser scan: we see that something is in the way, how high it is and which direction it lies in. When we name a building, it is the nearest mapped one in the same direction — that says where the obstruction is, not that this particular building casts the shadow. “Building” and “trees” say what kind of obstruction it is, not which one.
Slottsplassen 1 · SE (120°) · 38 m
The orange ring is the facade you chose. Grey shapes are buildings. The numbered wedges point at the obstructions in the list below. See the area in satellite imagery →
1. outbuilding/garage and treesblocks 76.4 hours a year · direction 52.3–61.3° · 24.9 m high · the nearest mapped outbuilding/garage in the same direction stands 217.8 m away · the laser scan sees the obstruction as trees 117 m awaySee this obstruction in satellite imagery →
2. building and treesblocks 51.3 hours a year · direction 164.3–171.3° · 20.8 m high · the nearest mapped building in the same direction stands 188.7 m away · the laser scan sees the obstruction as trees 78 m awaySee this obstruction in satellite imagery →
3. building and treesblocks 49.6 hours a year · direction 138.3–144.3° · 18.2 m high · the nearest mapped building in the same direction stands 238.2 m away · the laser scan sees the obstruction as trees 66 m awaySee this obstruction in satellite imagery →
Calculated from Kartverket's laser scan, flown 18 May 2024, with leaves on the trees. The sun is worked out geometrically for the sun's own centre, without clouds. December counts the leaves as dense, so the figure is a minimum. How?
The link re-runs the lookup in the service; it does not show a stored
answer. If we recompute, the link moves with us — and the figures on this page can then
lag a step behind until we update them.
An exception, stated plainly. The palace is drawn as a
relation in OpenStreetMap — several ways assembled into one surface — and until
August 2026 we fetched only ordinary ways, so the building was missing from our
map data. We now fetch both. In Matrikkelen the palace is building type 311, not a
dwelling, and Soltreff otherwise calculates dwellings only; the palace is the one
building we have made an exception for, because this page is about it and nobody lives
there who needs protecting. The figures for the moments and the street further up come
from a run of the same code on the same outline: the report shows one wall at a time,
and the street is in no report.
What we do not know. The palace has no registered dwellings, so the
report is for the ground level, and the storey heights in the model are derived from the
roof height with our default value — which gives nine nominal levels for a house that
has three real ones. The balcony's own height is not in any register we read. It makes
no difference to the answer here: the horizon in front of the facade is under three
degrees at all of those heights, and the sun stands at 37, so the front is in
sun whichever of them the balcony sits at. Had the answer depended on the height, we
could not have given it.
The conventions. Geometric sun for the sun's centre, no cloud — we
know nothing about the weather on 17 May. The sun is a disc a good half-degree across,
not a point, so the changeover between sun and shade is soft by a couple of minutes
either way (the method explains why). That is why the figures
here come with their margin: 35 degrees of clearance on the palace facade absorbs that
softness without trouble, a tenth of a degree in the street does not. Times are Norwegian
local time, with summer time. The elevation model is Kartverket's laser scan of 18 May 2024, with leaves on the
trees. If we recalculate the algorithm, we recalculate this page too.
Privacy. The palace is a public building with no registered dwellings,
and the parade route is a public street. There is no resident to consider here, as with
the two museum homes. That is also why this page is the third
and last address with figures in its text: every other sun figure on Soltreff is for a
home someone lives in, and those stay in the report, which is not indexed.
Check your own view
If you are watching the parade from a window or a balcony in the centre, Soltreff can
answer for that exact address — floor, wall and moment. The link below opens the service
at Akersgata 18, a residential building a block from the route, with the
moment already set to 17 May at 10.00, so you can see what the moment view does. What it
answers there stays in the report and not here: we calculate homes people live in, and we
do not put their figure on a page that can be searched.
We cover Oslo, Bergen, Trondheim, Stavanger, Kristiansand and Akershus for now, plus parts of neighbouring municipalities. The rest of Norway is coming.
